Cayenne contains a resinous and pungent substance known as capsaicin. This chemical relieves pain and itching by depleting certain neurotransmitters from sensory nerves. In a double-blind trial, application of a capsaicin cream to the skin relieved both the itching and the skin lesions in people with psoriasis.¹² Creams containing 0.025 to 0.075% capsaicin are generally used. There may be a burning sensation the first several times the cream is applied, but this usually become less pronounced with each use. The hands must be carefully and thoroughly washed after use, or gloves should be worn, to prevent the cream from accidentally reaching the eyes, nose, or mouth and causing a burning sensation. The cream should not be applied to areas of broken skin.

Fumaric acid , in the chemically bound form known as fumaric acid esters, has been shown in case studies,¹³ preliminary trials^{14 , 15 , 16} and double-blind trials^{17 , 18 , 19} to be effective against symptoms of psoriasis. However, because fumaric acid esters can cause significant side effects, they should be taken only under the supervision of a doctor familiar with their use. Nevertheless, these side effects have been reported to decrease in frequency over the course of treatment and, if they are closely monitored, rarely lead to significant toxicity.²⁰

A double-blind trial in Pakistan found that topical application of an aloe extract (0.5%) in a cream was more effective than placebo in the treatment of adults with psoriasis.²¹ The aloe cream was applied three times per day for four weeks.

In a double-blind trial, fish oil (10 grams per day) was found to improve the skin lesions of psoriasis.²² In another trial, supplementing with 3.6 grams per day of purified eicosapentaenoic acid (EPA, one of the fatty acids found in fish oil) reduced the severity of psoriasis after two to three months.^{23 , 24} That amount of EPA is usually contained in 20 grams of fish oil, a level that generally requires 20 pills to achieve. However, when purified EPA was used in combination with purified docosahexaenoic acid ( DHA , another fatty acid contained in fish oil), no improvement was observed.²⁵

Additional research is needed to determine whether fish oil itself or some of its components are more effective for people with psoriasis. One trial showed that applying a preparation containing 10% fish oil directly to psoriatic lesions twice daily resulted in improvement after seven weeks.²⁶ In addition, promising results were reported from a double-blind trial in which people with chronic plaque-type psoriasis received 4.2 g of EPA and 4.2 g of DHA or placebo intravenously each day for two weeks. Thirty-seven percent of those receiving the essential fatty acid infusions experienced greater than 50% reduction in the severity of their symptoms.²⁷

Supplementing with fish oil also may help prevent the increase in blood levels of triglycerides that occurs as a side effect of certain drugs used to treat psoriasis (e.g., etretinate and acitretin).²⁸

An ointment containing Oregon grape (10% concentration) has been shown in a clinical trial to be mildly effective against moderate psoriasis but not more severe cases.²⁹ Whole Oregon grape extracts were shown in one laboratory study to reduce inflammation often associated with psoriasis.³⁰ In this study, isolated alkaloids from Oregon grape did not have this effect. This suggests that there are other active ingredients besides alkaloids in Oregon grape. Barberry , which is very similar to Oregon grape, is believed to have similar effects. An ointment, 10% of which contains Oregon grape or barberry extract, can be applied topically three times per day.

In traditional herbal texts, burdock root was believed to clear the bloodstream of toxins.³¹ It was used both internally and externally for psoriasis. Traditional herbalists recommend 2 to 4 ml of burdock root tincture per day. For the dried root preparation in tablet or capsule form, the common amount to take is 1 to 2 grams three times per day. Many herbal preparations will combine burdock root with other alterative herbs, such as yellow dock , red clover , or cleavers . Burdock root has not been studied in clinical trials to evaluate its efficacy in helping people with psoriasis.

Although clinical trials are lacking, some herbalists use the herb, coleus , in treating people with psoriasis.³² Coleus extracts standardized to 18% forskolin are available, and 50 to 100 mg can be taken two to three times per day. Fluid extract can be taken in the amount of 2 to 4 ml three times per day.

Folic acid antagonist drugs have been used to treat psoriasis. In one preliminary report, extremely high amounts of folic acid (20 mg taken four times per day), combined with an unspecified amount of vitamin C , led to significant improvement within three to six months in people with psoriasis who had not been taking folic acid antagonists;those who had previously taken these drugs saw a worsening of their condition.³³

An ointment containing Oregon grape (10% concentration) has been shown in a clinical trial to be mildly effective against moderate psoriasis but not more severe cases.³⁴ Whole Oregon grape extracts were shown in one laboratory study to reduce inflammation often associated with psoriasis.³⁵ In this study, isolated alkaloids from Oregon grape did not have this effect. This suggests that there are other active ingredients besides alkaloids in Oregon grape. Barberry , which is very similar to Oregon grape, is believed to have similar effects. An ointment, 10% of which contains Oregon grape or barberry extract, can be applied topically three times per day.