A clinical trial compared the topical use of 5% tea tree oil to 5% benzoyl peroxide for common acne. Although the tea tree oil was slower and less potent in its action, it had far fewer side effects and was thus considered more effective overall.^[REF] The effectiveness of tea tree oil was confirmed in a six-week double-blind trial. In that study, participants applied a 5% tea tree oil gel to the affected area twice a day for 20 minutes and then washed it off with tap water.²

Several double-blind trials indicate that zinc supplements reduce the severity of acne.^3,4,5,6 In one double-blind trial,⁷ though not in another,⁸ zinc was found to be as effective as oral antibiotic therapy. Doctors sometimes suggest that people with acne take 30 mg of zinc two or three times per day for a few months, then 30 mg per day thereafter. It often takes 12 weeks before any improvement is seen. Long-term zinc supplementation requires 1–2 mg of copper per day to prevent copper deficiency.

One controlled trial found that guggul (Commiphora mukul) compared favorably to tetracycline in the treatment of cystic acne.⁹ The amount of guggul extract taken in the trial was 500 mg twice per day.

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.¹⁰ Burdock root tincture may be taken in the amount of 2 to 4 ml 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, none of these herbs has been studied in scientific research.

In a preliminary trial, people with acne were given 2.5 grams of pantothenic acid orally four times per day, for a total of 10 grams per day—a remarkably high amount.¹¹ A cream containing 20% pantothenic acid was also applied topically four to six times per day. With moderate acne, near-complete relief was seen within two months, while severe conditions took at least six months to respond. Eventually, the intake of pantothenic acid was reduced to 1 to 5 grams per day—still a very high amount.

Large quantities of vitamin A—such as 300,000 IU per day for females and 400,000–500,000 IU per day for males—have been used successfully to treat severe acne.¹² However, unlike the long-lasting benefits of the synthetic prescription version of vitamin A (isotretinoin as Accutane), the acne typically returns several months after natural vitamin A is discontinued. In addition, the large amounts of vitamin A needed to control acne can be toxic and should be used only under careful medical supervision.

A preliminary report suggested that vitamin B6 at 50 mg per day may alleviate premenstrual flare-ups of acne experienced by some women.¹³ While no controlled research has evaluated this possibility, an older controlled trial of resistant adolescent acne found that 50–250 mg per day decreased skin oiliness and improved acne in 75% of the participants.¹⁴ However, another preliminary report suggested that vitamin B6 supplements might exacerbate acne vulgaris.¹⁵