Milk thistle, also called lady's thistle, has a long history of use. It's considered possibly effective in easing heartburn and seasonal allergies when used with other herbs, according to Medline Plus. Milk thistle and one of its substances, a flavonoid called silymarin, are being studied widely for potential use in treating liver disease and tumor growth, although there's insufficient evidence of effectiveness. Some hair-growth products contain milk thistle as an ingredient, but there's no evidence they will help hair grow or stop hair loss.
Thin Evidence for Hair Connection
One hair-growth formula includes milk thistle along with 21 other ingredients, stating that the herb's antioxidants protect hair follicles. Milk thistle extract from plants -- not the seeds -- might, in fact, enhance effects of estrogen, Medline Plus says. But estrogen's role in hair loss is not completely understood. While milk thistle's effects are being widely studied in treating liver and other diseases, its role in hair loss -- whether for topical or oral use -- has not yet been studied. Milk thistle is generally thought safe to take, with mild side effects including stomach upset. Don't take it if you're pregnant or breast-feeding, or have health conditions or take medicines that effect estrogen; check with your doctor before taking it if you use any medications.