Citrus species (Citrus spp.), such as lemon, orange, and grapefruit, have a long history of traditional use in hair care, particularly in folk remedies aimed at improving scalp health, adding shine, or addressing dandruff. In traditional medicine systems, citrus extracts or juices are sometimes applied to the scalp and hair, based on beliefs that the acidity and vitamin C content can cleanse the scalp and promote healthier hair. However, there is minimal scientific evidence to validate these uses for treating hair loss or thinning. Most scientific studies focus on the antioxidant properties of citrus and their benefits for skin health, but not specifically for hair regrowth or the prevention of hair thinning.

Some cosmetic products may include citrus extracts for their fragrance, astringency, or purported ability to stimulate the scalp, but robust clinical trials or laboratory studies demonstrating efficacy for hair loss are lacking. As a result, while citrus spp. are used in traditional hair care practices, their application for hair loss or thinning is not supported by high-quality scientific evidence. The overall evidence rating for their effectiveness in promoting hair growth or preventing hair loss is low, reflecting limited traditional uses and a lack of substantial scientific validation.