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Hydrogels for Osteochondral
Tissue Engineering
Journal of Biomedical

(March 2020)
Anti-Wrinkle Activity
& Transdermal Delivery
of GHK Peptide
Journal of Peptide Science
(March 2020)
Pulsed Glow Discharge
to GHK-Cu Determination
International Journal
of Mass Spectrometry

(March 2020)
Protective Effects of GHK-Cu
in Pulmonary Fibrosis
Life Sciences
(January 2020)
Anti-Wrinkle Benefits
of GHK-Cu Stimulating
Skin Basement Membrane
International Journal of Molecular Sciences
(January 2020)
Structural Analysis
Molecular Dynamics of
Skin Protective
TriPeptide GHK
Journal of Molecular Structure
(January 2020)
In Vitro / In Vivo Studies
pH-sensitive GHK-Cu in
Superabsorbent Polymer
GHK Enhances
Stem Cells Osteogenesis
Acta Biomaterialia
Antibacterial GHK-Cu
Nanoparticles for
Wound Healing
Particle & Particle (2019)
Effect of GHK-Cu
on Stem Cells and
Relevant Genes
OBM Geriatrics
GHK Alleviates
Neuronal Apoptosis Due
to Brain Hemorrhage
Frontiers in Neuroscience
Endogenous Antioxidant
International Journal of Pathophysiology and Pharmacology (2018)
Regenerative and
Protective Actions of
GHK-Cu Peptide
International Journal of
Molecular Sciences
Skin Regenerative and
Anti-Cancer Actions
of Copper Peptides
GHK-Cu Accelerates
Scald Wound Healing
Promoting Angiogenesis
Wound Repair and

GHK Peptide Inhibits
Pulmonary Fibrosis
by Suppressing TGF-β1
Frontiers in Pharmacology
Skin Cancer Therapy
with Copper Peptides
The Effect of Human
Peptide GHK Relevant to
Nervous System Function
and Cognitive Decline
Brain Sciences (2017)
Effects of Tripeptide
GHK in Pain-Induced
Aggressive Behavior
Bulletin of Experimental
Biology & Medicine
GHK-Cu Elicits
In Vitro Alterations
in Extracellular Matrix
Am Journal of Respiratory
and Critical Care Medicine

Selected Biomarkers &
Copper Compounds
Scientific Reports

GHK-Cu on Collagen,
Elastin, and Facial Wrinkles
Journal of Aging Science
Tri-Peptide GHK-Cu
and Acute Lung Injury

Effect of GHK Peptide
on Pain Sensitivity
Experimental Pharmacology

New Data of the
Cosmeceutical and
TriPeptide GHK
SOFW Journal
GHK Peptide as a
Natural Modulator of
Multiple Cellular Pathways
in Skin Regeneration
BioMed Research (2015)
Resetting Skin Genome
Back to Health
Naturally with GHK
Textbook of Aging Skin
GHK-Cu May Prevent
Oxidative Stress in Skin
by Regulating Copper and
Modifying Expression of
Numerous Antioxidant Genes Cosmetics (2015)
GHK Increases
TGF-β1 in
Human Fibroblasts

Acta Poloniae

The Human Skin Remodeling Peptide Induces Anti-Cancer
Expression and DNA Repair Analytical Oncology
Resetting the
Human Genome to Health
BioMed Research
Enhanced Tropic Factor Secretion of Mesenchymal
Stem Cells with GHK
Acta Biomater
Anxiolytic (Anti-Anxiety)
Effects of GHK Peptide
Bulletin of Experimental
Biology & Medicine
Lung Destruction and
its Reversal by GHK
Genome Medicine
TriPeptide GHK Induces
Programmed Cell Death
of Neuroblastoma
Journal of Biotechnology
Stem Cell
Recovering Effect
of GHK in Skin
Peptide Science
Skin Penetration of
Copper Tripeptide in Vitro
Journal of International
Inflammation Research
Possible Therapeutics
for Colorectal Cancer
Journal of Clinical and
Experimental Metastasis
Methods of Controlling
Differentiation and
Proliferation of Stem Cells
Effects of
Copper Tripeptide
on Irradiated Fibroblasts
American Medical Association
Avoid Buying Fake Copper Peptides Dangerous

Avoid Buying Fake Copper Peptides Dangerous CLICK HERE TO FIND OUT

Avoid Wasting Your Money & Damaging Your Skin!

Would you trust an untrained “physician” or “dentist” to operate, perform a procedure, or even to give you advice? Why not? Because your health is important to you.

In this manner, would you trust just any online company selling supposed GHK or copper peptides with something as important as your skin? Of course not. At best you would be wasting your money, at worst your skin might be damaged.

What Are True Skin Rejuvenating Copper Peptides?
Rejuvenating copper peptides are small protein fragments that can bind copper 2+ ions. When used in topical cosmetic products they result in very positive for skin rejuvenation. These are GHK (glycyl-l-histidyl-l-lysine) and the mixed second generation copper products promote skin health.

However, not all copper peptides help the skin. Some snake venoms contain very toxic copper peptides.

These are copper peptides, that have been shown to improve to help skin beauty and condition, have been heavily tested by leading dermatologists and the results in published in journals. I have has researched copper peptides and their biological actions for over 45 years, am still researching to this very day, and published many papers and patents of them.




AnthonyFrederickSandys_Augustus-ortraitofCyrilFlowerLord_BatterseaStrange Copper Peptides Being Sold

1. They have too little GHK-copper to be effective.
Some copper peptide products on the market have much too little copper to be effective. Copper 2+ is a vibrant blue so you would expect a solution with a high copper content to be quite blue in color, such as this true 1% GHK-Cu serum (shown in the picture on the right).

Unfortunately, consumers have no real way to know what they are truly buying. We simply want to educate those visiting our website and make sure all of you are well informed.



2. Don't use GHK-copper with EGF (Epidermal Growth Factor)
Mixing EGF and copper peptides is a bad idea. Very little EGF can penetrate the skin. I can find no credible evidence that EGF in cosmetics actually improves skin.

If enough EGF penetrated the skin to have an effect, then there are the toxicity problems of EGF. Wound healing studies with EGF were stopped because the EGF built up in the blood stream. Furthermore, EGF causes serious hair loss. The injection of 2 milligrams of EGF into sheep causes all the wool hair to fall out within a week. Stem cells for the skin arise from the hair follicles and the EGF shuts them down.

Science 24 July 1998: Vol. 281. no. 5376, p. 511
First man tamed fire. Then he invented agriculture. Now, after 5000 years of shearing sheep by hand, he's created Bioclip, which leaves the job to the sheep. Bioclip is based on a common protein called epidermal growth factor (EGF). Discovered 2 decades ago by biochemist Stanley Cohen of Vanderbilt University in Nashville, Tennessee, EGF stimulates the growth of various types of tissues in animals and causes one type of sheep to molt periodically. CSIRO, the Australian research agency, has spent 20 years looking into how to harness EGF in the sheep industry and has now incorporated it into a biological substitute for shears. At shearing time, says Pat Wilson of CSIRO's animal production facility, a sheep gets an injection of Bioclip and is then fitted with a net that catches the fleece as it falls off, a process that takes about a week. Wilson and the company, Bioclip Pty Ltd. in New South Wales, say they will launch the product commercially in October and anticipate a big demand: The country's $3-billion-a-year wool industry produces 70% of the world's clothing wool. Soon barns Down Under may no longer ring with the sounds of spring shearing--instead, there will be 150 million merinos milling around in hairnets.

3. Unknown Skin Experts
With all the explosive breakthroughs of copper peptide products in recent scientific literature, there has been a complementary growth of copper peptides on the market. Most of these copper peptides are pale comparisons (often times literally) to the original copper peptides discovered by myself.

There are many new Internet skin experts giving advice on copper peptides. They claim various relevant degrees and knowledge. But almost always we can find no evidence of awarded degrees from real universities. We also check the scientific literature for publications or patents and can find nothing. For the record, I have a BA in Chemistry and Mathematics from the University of Minnesota and a PhD in Biochemistry from the University of California at San Francisco. You can easily find my publications by searching "Pickart copper peptides"on the internet.

4. Strange mixtures that can inhibit skin renewal
Copper peptide products with too many ingredients tend to work poorly. When I founded Procyte Corporation to develop copper peptide products, I first tested many creams and ointments used clinically on wounds. Very few of these worked well with GHK-copper. Most just cancelled out the copper peptide effects.

5. Some copper complexes may be toxic
Many copper complexes are extremely toxic. For five years, I worked with the Chemistry Department at the University of Washington designing and testing toxic copper complexes for use as anti-cancer drugs. This is why one must be very careful mixing GHK with various ingredients. One well known GHK-copper cream contains triethanolamine. If this obtains copper, then it kills the skin repair fibroblasts when present at a very low concentration.

5.1 David K. Johnson, Terrance B. Murphy, Norman J. Rose, William H. Goodwin, Loren Pickart, Cytotoxic chelators and chelates 1. Inhibition of DNA synthesis in cultured rodent and human cells by aroylhydrazones and by a copper(II) complex of salicylaldehyde benzoyl hydrazone, Inorganica Chimica Acta 01/1982; 67:159-165.

5.2 Loren Pickart, Anti-neoplastic analogs of the growth factor glycyl-L-histidyl-L-lysine copper(II), Inorganica Chimica Acta 01/1983; 79(1-6):305-306 Inhibition of the growth of cultured cells and an implanted fibrosarcoma by aroylhydrazone analogs of the Gly-His-Lys-Cu(II) complex.

5.3 Loren Pickart, William H. Goodwin, William Burgua,Terrance B. Murphy, David K. Johnson, Inhibition of the growth of cultured cells and an implanted fibrosarcoma by aroylhydrazone analogs of the Gly-His-Lys-Cu(II) complex. Biochemical Pharmacology 01/1984; 32(24):3868-71.

5.4 W E Antholine, S Lyman, D H Petering, L Pickart,,Formation of adducts between cupric complexes of known antitumor agents and ehrlich ascites cells, Biological and Inorganic Copper Chemistry, Edited by K. D. Karlin, J. Zubieta, 01/1985: chapter Formation of Adducts Between Cupric Complexes of Known Antitumor Agents and Ehrlich Ascites Tumor Cells: pages 125-137; Adenine, Guilderland, NY, 1985.

Questions or Advice?

Email Dr. Loren Pickart at

Call us at 1-800-405-1912 Monday Through Friday (8 am to 6 pm) PSTLoren Pickart Skin Biology Facebook

Fairy Dust (Angel Dusting) and Misleading Cosmetic Ingredients

Angel Dusting: The cosmetic companies often add one active molecule to a skin cream along with 200 million inactive molecules, then claim that their product has the therapeutic benefits of the active molecule.

Fairy Dust (also known as angel dusting or window dressing) is a cosmetic industry phrase that refers to using misleading cosmetic products that potentially might have helpful actions but in a way that is unlikely to produce any significant biological effects in skin or hair. For example, vitamin C is often used at low concentrations or at an inappropriate pH range. The vitamin C has no effect on skin but the advertising for this misleading cosmetic product implies that it has wonderful actions on a person's skin. Likewise, water is essential for skin health, so any product with water is called beneficial for skin.

Angel dusting skin products from the cosmetic industry that contain collagen, elastin, or DNA have no effect of the skin's production of collagen and elastin and have no effect on the skin's firmness or elasticity, and also have no effect on the rate of skin renewal. These fairy dust ingredients only serve to attract water to the surface of the skin (the worst possible effect would be if the bovine collagen and elastin in cosmetics gave you the prions that cause Mad Cow Disease ). Only collagen and elastin that is produced within the skin helps improve skin firmness and elasticity.

Do 62 Ingredients Make a Better Skin Cream?

No. This is similar to children learning to cook. At some time, they decide to mix everything good in the kitchen - sugar, spices, milk, eggs, oils, salt, flour, and so on. Of course, the result is a mess.


Paris Loves Chemical Optical Diffusers and "Fairy Dust" Cosmetics

Once I gave a talk at a large skin company in the south of Paris. I explained that many effects of aging and sun damage on skin could be reversed and that it is possible, in many respects, to return the biology of human skin to that of a much younger person. The company's research director said this was not necessary because the illusion of young skin could be created very easily with a mixture of dyes and chemical optical diffusers (this light diffusing is found in many make up products). I told him that this is just painting the skin and that he did not understand skin biology and biochemistry. After my statement, the meeting was immediately terminated and I was escorted outside to the street to find a taxi back to my hotel. On the other hand, setbacks in these same areas lower testosterone production further complicating these difficulties.

Products with Bioactive Ingredients That People Often Ask Us About

How It Works
Act by irritation that stimulates new skin repair
1. Increases collagen and elastin synthesis
2. Increases skin thickness
Used Clinically
for Skin Repair?
Effects are slow
Can be irritating
Often work better if followed by a breakdown-resistant copper peptide product


How It Works
Vitamin C helps collagen synthesis and acts as antioxidant
Increases collagen production but less than copper-peptides
Used Clinically
for Skin Repair?
NO - Effects on skin are too small
Must be very acidic (pH=2.5) for best effects


(ALA, Vitamin E, CoQ-10, Tocotrienols, etc)
How It Works
Protectants that reduce skin damage from oxygen radicals
Depends on natural skin renewal processes - very slow improvements
Used Clinically
for Skin Repair?
NO - Effects are too mild
None at low levels, some cause acne at high levels.


How It Works
Stimulate macrophages
Minor skin improvements
Used Clinically
for Skin Repair?
No - Effects on skin too small for clinical use
Safe on skin


EDF (Epidermal Growth Factor)
IGF (Insulin Growth Factor)
How It Works
Replaces a critical growth factor protein
Increases skin re-epithelialization
Used Clinically
for Skin Repair?
NO - EGF clinical studies stopped because of toxicities
NO - IGF was not effective enough
EGF causes hair loss and gastric upset.
Used commercially to remove wool from sheep.


How It Works
Increasing proteins in the skin
Thickens and hardens skin
Used Clinically
for Skin Repair?
NO - Such peptides produced heavy scarring in clinical studies
May produce a hardened skin or the "moon-face" look of pregnant women

Damaging Skin Products

A negative aspect of cosmetic companies is the promotion of ineffective and often skin-damaging cosmetic beauty products. Many facial "serums" and "renewal" creams are no more than chemicals formerly used as hair hardeners that put a brief film of resin over the skin. It is like putting varnish on your face. Compounds known to be skin irritants for 40 years are still put into skin creams because they make a cream that looks good immediately after application to the skin. Liposome-containing skin creams were marketed as miracle skin youth enhancers, but seem to be vanishing along with the youthful appearance of the users of the liposome creams. During our analyses of skin-care cosmetic beauty products from other companies, we often detect chemicals such as coloring agents and other organic chemicals that are not listed on the ingredient list because they are under 1% in concentration.

Avoid Skin Oxygenating Products

Certain cosmetic beauty products are sold to increase skin oxygenation. This is done either by (1) covering the face with a mask and running a flow of pure oxygen over the face for about an hour, or (2) covering the skin with certain chemicals that carry extra oxygen into the skin. If skin is damaged, this method may cause an improvement in skin in a few days.

The problem with this method is that it will cause long-term skin problems. By artificially increasing the oxygen level in your skin, your body will decrease the blood vessels (capillaries) that feed oxygen and nutrients to the cells of your skin. Capillaries grow towards areas of the body that are low in oxygen. By adding more oxygen to the outer layers of your skin, your cells will have less oxygen and nutrients from your body. Your skin will age faster because of inadequate nutrients from the blood and your skin will be more pale and grayish because of fewer red blood cells in your skin.

Companies that sell these cosmetic beauty products say that oxygen applied to the skin has been used to heal wounds faster in hospital studies. This is true, but these types of wounds and skin ulcers are temporary and emergency therapies to heal over the wound and reduce the chance of infection. Long-term application of high oxygen to your skin's surface will not heal the health of normal skin.

Gerontologists consider the cellular degeneration caused by chronic exposure to elevated concentrations of oxygen (hyperoxia) as a model for accelerated aging at the cellular level. In cultured mammalian cells, elevated oxygen causes progressive growth inhibition, loss of reproductive capacity, and chromosomal breakage. The earliest effect of high oxygen is an inhibition of mitochondrial respiration which is in similar to aging theories that attribute much cellular aging to loss of mitochondrial functions1.

Skin Lightening Chemicals - Products with a Skin Bleaching Agent

Increased melanin deposition resulting in hyperpigmentation may be a sign of hormonal changes, pregnancy, chemical exposure, or some pharmaceutical drugs.

Skin lightening treatments using a skin bleaching agent often use 2% to 4% hydroquinone in an alcoholic glycol or cream base that is applied daily. Hydroquinone cream (using a skin bleaching agent) decreases melanin production by deactivating tyrosinase. It is usually most effective when applied over the entire face rather than specifically at hyperpigmented sites. Hydroquinone cream is effective for only as long as it is used. After stopping treatment; normal levels of tyrosinase will be present within two or three days and treatment is required indefinitely to maintain results.

Retinoic acid (tretinoin, Retin-A) has melanin-blending properties and the combination of retinoic acid and hydroquinone cream gives more even distribution of pigmentation. The ratio of retinoic acid and hydroquinone can be adjusted to achieve the desired balance of bleaching and blending. In persons with vitiligo (the appearance of de-pigmentated patches of skin), physicians use a higher ratio of retinoic acid to hydroquinone, to achieve the maximum blending with minimum skin bleaching agent.

Before use, the hydroquinone patch tested for a week before using to determine a person's tolerance of the chemical. When outside, a reflective sunscreen of SPF 15 or greater should be used to avoid suntanning. But Skin Biology DOES NOT recommend the use of hydroquinone.

Other products that are also used as a skin bleaching agent are kojic acid, arbutin, ascorbic acid, botanical lighteners, and glycolic acid.

Products Containing "DNA"

Some cosmetic beauty products have appeared on the market in the last few years that contain DNA (deoxyribonucleic acid) among their ingredients. These product sound impressive, as every high school student knows DNA is essential to life and makes up a large part of our skin. However, DNA plays no role in external skin creams, other than to raise the price.

DNA cannot penetrate the skin and even if it did, it could not penetrate the skin's cells. Products advertising DNA (from animals or yourself) as a part of your skin care regimen exploit customers confusion about the role of DNA and how it can (and cannot) be used.

Avoid Skin Damaging Corticosteroids

Corticosteroids (or often just called "steroids") such as cortisone and prednisone are heavily used for the treatment of various skin irritations and dermatitis. They give immediate results in terms of reducing skin inflammations but produce damaged and thinned skin (often 50% to 60% thinner) by inhibiting the natural skin repair processes. The immune cells (white cells) both cause skin inflammation and skin healing. Corticosteroids act like sledgehammers and stop both processes - both the inflammation and the skin repair. In experimental wound healing studies, cortisone is often used to delay healing by mimicing the action of poorly-healing wounds. Cortisone also causes skin bruising - usually at the upper limbs and forearms and especially at doses greater than 7.5 mg/day, and the incidence of viral, bacterial and mycotic infections.

Use of corticosteroids produces a vicious cycle requiring more corticosteroid use due to more irritations from the weakened skin. The use can promote diabetic conditions, thymus involution, immune suppression, the spread of cancers, bone damage, and cataracts. It is estimated that 5,000 hip replacements yearly in Canada are due to overuse of corticosteroids.

A Serum to Avoid - Colorless Copper

Colorless copper is copper ion (+1) and has never been found to have significant skin renewal effects. Copper products that are blue or green are based on copper ion (+2) which is blue in water and produces products that are either blue or green depending how they are mixed with other ingredients.

The only copper form that the FDA allows for clinical use on wounds and skin transplants is the blue form of copper. All the numerous studies from Universities around the world that found positive effects on skin repair and tissue regeneration used the blue form of copper. The natural activator of skin repair in the human body, Gly-His-Lys-Copper(II), has the blue form of copper.


Skin Hardening Peptides

Like a Callus, Collagen-Stimulating Peptides (Pentapeptides and Amino Peptides) May Harden Skin and Produce Scarring

The latest "Hot Product" sold by cosmetic companies, and aging actresses on late night cable channels, are products with peptides claimed to improve skin by increasing the production of collagen and elastin, and proteoglycans. These peptides are similar in action to substances intensively tested in wound healing skin studies about 10 years ago. These peptides are compared by the manufacturer to actions of transforming growth factor beta 1.

1. All skin renewal proteins and peptides are based on some aspect of skin repair and wound healing skin. In the early stages of wound repair, there is a very high synthesis of of proteins used to close the wound and produce a scar that rapidly covers and protects underlying tissues. This process can also produce hard calluses on hands and feet. In the later stages of healing, the scar tissue is removed and the skin is "remodeled" into a smoother, scarless surface.

Transforming Factor Beta was named because it made normal cells grow more like cancer cells but this does not mean it causes cancer. However, some researcher think it may speed the growth of breast cancers and play a role in the development of kidney failure.

Early stage wound repair factors such as TGF beta 1 (developed by Amgen Corporation) and RGD-collagen binding peptides based on fibronectin and collagen (developed by Telios Corporation) produced a strong stimulation of the production of collagen and elastin, proteoglycans and so on. However, these molecules failed to become wound repair products because, while they rapidly healed wounds, they also produced heavy and unacceptable scarring.

2. These peptides are said to be as effective as retinol on wrinkle reduction but said to be less irritating. The comparison to retinol and wrinkle reduction seems to be an attempt to confuse the consumers. Retinol has only a modest action on wrinkle reduction and is not very irritating. On the other hand, retinoic acid (such as used in Retin-A or Renova) has significant wrinkle reduction but can be very irritating.

3. To get any skin effects with such peptides, they must be used at high concentrations (3% to 8%) in the product. Most cosmetic companies only use trivial amounts of any potentially beneficial substance.

4. Despite the heavy promotion of these products, there are no published papers on the skin effects of these new "breakthrough" peptides in any credible scientific journal. One of the widely circulated studies is by a French professor who has apparently has never published a reviewed paper in a major journal in the past 30 years, at least as recorded by the National Library of Medicine in Medline (See

This is baffling since France is filled with superb skin researchers. Why does not a corporation that sells billions of dollars in products yearly have its great breakthrough products tested by well known and respected skin researchers?

In contrast, the studies to determine the effectiveness of retinoic acid on skin remodeling and wrinkle reduction were funded by Johnson & Johnson for many years. Studies were performed by highly regarded, independent skin researchers.

5. Will these products give you a hard, insect-like exoskeleton? This is unlikely since these peptides must be present in concentrations of 5% to 8% in the product. Cosmetic companies are famous for putting in minuscule amounts of any potentially active factor. For example, effects on skin with retinol require about 0.6% retinol in the product. But some highly advertised retinol products have as little as 0.001% retinol. So the amount of peptide in the cream is likely to be very low.

6.On the positive side, such types of peptides could prove valuable for filling in skin defects, and hardening feet of long distance runners, and the hands of practitioners of karate and taekwondo.

Comparison of Skin Remodeling Copper Peptides
and TGF-like Peptides Effect

  Skin Remodeling
Copper Peptides
TGF-like Peptides
Function in the
human body
Late stage wound repair or skin remodeling, removal of damaged tissue and scars, and replacement with normal skin. Early stage wound coverage with protective scar.
Increase production
of skin proteins
(Collagen and Elastin, and Proteoglycans)
Rebuild blood
capillary networks
Remove damaged
proteins from skin
Anti-oxidant and
inflammatory actions
Very potent anti-oxidant
and anti-inflammatory
Repair skin barrier

Plant Extracts Are Often Toxic To Skin

Even natural plant products can damage skin. Many skin care companies advertise the value of various combinations of exotic plant extracts in their products. This is no assurance of safety or effectiveness. Many plants avoid being eaten by insects, birds, and mammals because they are filled with poisons and carcinogens which can irritate and damage skin. When evaluating skin products, one should always ask the salesperson where to find published, independent clinical studies that support the product claims (but don't expect to see any from the cosmetic industry).

Certain plants such as aloe and comfrey (which contains allantoin) have traditionally been used as healing agents. Many plants or plant extracts have medicinal value when used in strictly controlled conditions, but can cause discomfort, injury and death in other circumstances. Buttercups traditionally were used externally to relieve pain but can cause severe skin irritation. Foxglove is the commercial source of the well-known heart drug, digitalis, but is often fatal to grazing cattle. Often different species of animals are sensitive to plants - woolly paperflower plant is toxic to sheep but not cattle.

Most plants avoid being eaten by insects, birds, and mammals because they are filled with poisons and carcinogens which can irritate and damage skin. We all know about the problems with poison ivy, poison oak and poison sumac in North America. In Texas, more than 100 species of plants that are toxic to grazing cattle have been identified. For example, sacahuista causes photosensitization (hyper-reaction to sunlight), which results in inflammation, swelling and sloughing of the skin. Chronic poisoning from perennial broomweed usually causes pregnant cattle to abort. Plants which produce toxic amounts of prussic acid (i.e., sorghum species) can kill cattle within 15 minutes. In contrast, threadleaf groundsel may not produce illness or death for one year after consumption. Threadleaf groundsel poisons the liver, while bitterweed, oaks and sacahuista cause nitrate poisoning. African rue, western bitterweed, twinleaf senna, whitebrush and mesquite all poison cattle.

Even plants that contain beneficial compounds often are poisonous as pure plant extracts. Extracts of St. John's-Wort are used to combat depression and the plant is mentioned in Gerard's Herbal (late 16th Century) as a "a moste precious remedie for deepe woundes, or any wound made with a venomed weapon", but the plant is very poisonous to cattle.

Many skin products are marketed without safety testing and exotic plant extracts have high incidences of skin irritation. Some natural plant extracts fall outside the definitions of cosmetic ingredients and have never been tested for safety. Many skin care companies advertise the value of various combinations of exotic plant extracts and "fairy dust" or "angel dusting" cosmetics in their products but provide no independent clinical studies that support the product claims.

Foods, plants and trees that may cause primary irritant dermatitis

Tomato Dieffenbachia Rubber Tree
Carrot Castor Bean Fig Tree Sap
Mushroom Daffodil  
Cucumber Buttercup  
Parsnip Foxglove  
Turnip Tulip Bulb  
Parsley Narcissus Bulb  
Celery Cowslip