There are only a small number of all-natural products that have been rigorously tested for safety and efficacy in order to gain FDA-approval as prescription medicines.
Vitamin A (retinol) can be found in over-the-counter creams and cosmetics because of its mild exfoliating effects. Vitamin A acid (tretinoin) is the more potent form. Tretinoin cream is approved for acne (Retin-A) and fine wrinkling, pigmentation, and rough texture of facial skin (Renova). A different form of vitamin A called isotretinoin is approved for severe nodulocystic acne. It was originally named Accutane and is still available as a generic prescription medicine.
The active form of vitamin D is called calcitriol or vitamin D3. Oral vitamin D3 is effective for psoriasis, but it is not approved for that purpose because it causes elevated calcium levels in the blood. However, it is approved as a treatment for low calcium levels in people with kidney failure. Vitamin D3 is also approved as an ointment for the treatment of psoriasis (brand name Vectical).
Botanicals—Chemicals derived from plants
The first compounds of interest to dermatologists are the psoralens. These chemicals are found in a variety of fruits and vegetables such as lemons, limes, celery, parsnips, and figs. When they are ingested or their juices are applied to skin, the skin becomes more sensitive to the sun and may burn, blister, and darken. The ancient Egyptians discovered this fact and used psoralens to treat the depigmenting skin disease called vitiligo. Psoralens are also used now to treat psoriasis along with exposure to long-wave ultraviolet light (UVA).
Another important compound is podophyllotoxin extracted from the resin of the common May apple plant grown in the eastern U.S. A solution of 25% resin with benzoin in alcohol is applied in the office as a treatment for external genital warts and perianal warts caused by certain types of the human papillomavirus (HPV). Podophyllotoxin is now available as a prescription gel or solution in a concentration of 0.5% for home use.
In 2010, another ointment was approved for the treatment of external genital warts. It is called Veregen. It contains 15% catechins which are chemicals extracted from green tea leaves. It is not synthesized in the lab.
The most recent addition to the prescription botanical list is derived from the common croton plant Euphorbia. The chemical called ingenol mebutate (brand name Picato) is formulated into a gel for the treatment of actinic keratoses on chronically sun-damaged skin. These are the most common precancerous skin lesions that may develop into a serious skin cancer if left untreated.