Barberry (Berberis vulgaris), coptis (Coptis chinensis), goldenseal (Hydrastis canadensis), or Oregon grape root (Berberis aquifolium) in tincture form taken in the amount of one-fourth to one-half teaspoon in one-fourth cup of water three times a day should provide some help. The active substance, berberine, kills bacterial and fungal nail infections. Berberine is an alkaloid that has been found to have microbial properties on bacteria, fungi, protozoans and Chlamydia . CAUTION: Do not use any of these herbs if pregnant or with gallbladder disease. Do not use for more than two weeks at a time or when taking a Vitamin B6 supplement or a protein supplement with histadine. Goldenseal should not be used by anyone with cardiovascular disease or glaucoma.
Tea Tree Oil (Melaleuca alternifolia)
Tea tree oil, also called cajeput oil, comes from a twenty to twenty-five foot tall tree. The bark of the tree consists of paperlike layers. The oil is made from distilled leaves and small branches. Native Australians used this oil as an antiseptic. Supposedly Captain Cook gave the tree its name. The oil contains a disinfectant and antiseptic that acts against many different bacteria and fungi. A double-blind, randomized and multicenter trial of the use of tea tree oil on onychomycosis infections was conducted at the University of Rochester School of Medicine and Dentistry. The results found that tea tree oil worked as well as clotrimazole (Lotrimin or Mycelex), a topical anti-fungal preparation . Tea tree oil should be applied full strength once a day in the evening. It may take three to six months for full effectiveness.
Take Lactobacillus or another probiotic daily, which should help restore helpful bacteria that can control both bacterial and yeast infections.
If nails have become weak or brittle from an infection, take 500 mg of black current oil twice a day. This may need several months of regular use to see a change.
Tincture of iodine was used for many years to treat fungal nail infections.
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 Berberine report by Ray Sahelian, M.D. with bibliography
 Buck, DS, et al. “Comparison of two topical preparations for the treatment of onychomycosis: Melaleuca alternifolia (tea tree) oil and clotrimazole,” The Journal of Family Practice 1994 Jun;38(6):601-5.