In a double-blind study, supplementing with zinc (23 mg three times per day for three months) decreased the severity of rosacea by about 75%, whereas no improvement occurred in the placebo group. Mild gastrointestinal upset was reported by 12% of the people taking zinc, but no other significant side effects occurred.¹ Long-term zinc supplementation should be accompanied by a copper supplement, in order to prevent zinc-induced copper deficiency.

Some people with rosacea have been reported to produce inadequate stomach acid.² In a preliminary trial, supplemental hydrochloric acid, along with vitamin B complex, improved some cases of rosacea in people with low stomach-acid production.³ Similarly, improvement in rosacea has been reported anecdotally after supplementation with pancreatic digestive enzymes, and a controlled study found that rosacea patients produced less pancreatic lipase than healthy people.⁴ Controlled trials are needed to evaluate the effects of hydrochloric acid and digestive enzyme supplements in rosacea. Hydrochloric acid supplements should not be taken without the supervision of a healthcare practitioner.

Historically, tonic herbs, such as burdock, have been used in the treatment of skin conditions. These herbs are believed to have a cleansing action when taken internally.⁵ Burdock root tincture may be taken in 2 to 4 ml amounts per day. Dried root preparations in a capsule or tablet can be used at 1 to 2 grams three times per day. Many herbal preparations combine burdock root with other alterative herbs, such as yellow dock, red clover, or cleavers. In the treatment of acne rosacea, none of these herbs has been studied in scientific research.

Some people with rosacea have been reported to produce inadequate stomach acid.⁶ In a preliminary trial, supplemental hydrochloric acid, along with vitamin B complex, improved some cases of rosacea in people with low stomach-acid production.⁷ Similarly, improvement in rosacea has been reported anecdotally after supplementation with pancreatic digestive enzymes, and a controlled study found that rosacea patients produced less pancreatic lipase than healthy people.⁸ Controlled trials are needed to evaluate the effects of hydrochloric acid and digestive enzyme supplements in rosacea. Hydrochloric acid supplements should not be taken without the supervision of a healthcare practitioner.

Preliminary reports in the 1940s claimed that rosacea improved with oral supplements or injections of B vitamins^9,10,11 On the other hand, one report exists of rosacea-like symptoms in a patient taking 100 mg per day of vitamin B6 and 100 mcg per day of vitamin B12; these symptoms subsided when the supplements were discontinued.¹² More research is needed to evaluate the potential benefits or hazards of B vitamins for rosacea.