Nettle root extract is a common ingredient found in hair products to stimulate hair growth and is believed to be effective for treating both male and female pattern 
baldness. Nettle root is also taken orally as a vitamin supplement.
The common or stinging nettle is a flowering plant with hollow stinging hairs on its leaves and stems, which act like hypodermic needles and inject chemicals that produce a stinging, burning sensation when they come into contact with skin. The nettle plant has a long history of use as a medicine, as a food source, and as a source of fiber.
The effectiveness of nettle root for hair loss has not been thoroughly studied. However, research shows that this herb can block production of the hormone dihydrotestosterone (DHT), which is mainly responsible for hair loss - known as androgenic alopecia. DHT is the active form of testosterone and is 15-30 times more biologically potent than testosterone.
Only 2% of total testosterone in the blood is free and only free testosterone is biologically active. A protein known as sex hormone binding globulin (SHBG) binds to the remaining 98% of testosterone, keeping it inactive. When consumed, nettle root binds to SHBG instead of testosterone, increasing levels of free testosterone in men and estrogen in women.
To perform its biological functions, DHT binds to so-called ‘receptor sites’ for testosterone and DHT in the body. Nettle root competes with DHT for these receptor sites in the scalp, meaning that DHT is unable to interfere with hair growth.
Nettle root also directly blocks the enzyme that causes hair loss in androgenic alopecia and can be used as a stand-alone herb for treating male pattern baldness.
Additionally, women suffering from female pattern baldness have also seen positive effects with the use of topical solutions such as creams, lotions, shampoos and conditioners. Besides blocking production of excess DHT, topical nettle applications are thought to stimulate the scalp, strengthen the hair shaft, and stimulate the roots of the hair.
However, it may be a good idea to perform an allergy patch test or consult a medical professional before using nettle supplements or topical solutions, as some users have reported allergic reactions.
Having healthy, vibrant hair is important for both men and women. As we age, hair maintenance becomes even more important than ever before. If you’re unsure about what you can do to take care of your hair, there are natural supplements formulated with targeted nutrients that have been shown to support hair health, including nettle root extract. Natural supplements can be safe, effective alternatives to traditional cosmetic-based approaches.
Source:
Can Nettle Root Protect Against Hair Loss?