Does Low Testosterone Cause Hair Loss?

Take-home points

• Testosterone promotes the growth of body, pubic, and facial hair, but may in turn contribute to hair loss on the scalp in some individuals.
• Androgenic alopecia, in other words, hair loss caused by sex hormones, is potentially linked to an increase in DHT produced by testosterone. 
• More research is needed to better understand the role of testosterone on hair loss. 

‍What is testosterone? 

Testosterone is an androgen hormone, a group of hormones responsible for developing secondary sex characteristics (pubic hair, muscle mass).¹ Testosterone has many functions, including the growth of facial and pubic hair, the production of red blood cells and sperm, the development of genitals, muscle and bone mass, and it also regulates libido.^1,2  ‍

How does testosterone affect hair? 

Androgen hormones (including testosterone) stimulate the growth of more visible body hair during puberty (e.g., beard) and continue increasing different hair follicles and hair sizes for many years.^3,4 Paradoxically, however, androgens are thought to simultaneously stop the growth of specific scalp follicles (follicles on the head), which can cause balding (also known as androgenetic alopecia).^3,5,6 

There is, unfortunately, a lack of evidence within humans exploring the relationship between different levels of testosterone specifically and hair loss.

Does low testosterone cause hair loss

Hair loss linked to the body’s sex hormones is called androgenic alopecia and is thought to be caused by dihydrotestosterone (DHT). DHT is a hormone made by testosterone and erodes fat tissue around the hair follicle, which ordinarily protects it by acting as a cushion and keeping hair hydrated.⁸ 

As a result, the pressure from the weight of the scalp combined with this lack of a protective layer could be what causes androgenic alopecia. An increase in testosterone leading to increased DHT could cause hair loss. It may explain why some men with low testosterone experience hair loss as a side effect of testosterone treatment.⁸ 

Importantly, not all hair follicles are sensitive to DHT, so hair loss is not experienced all over the body and tends to be localised to the scalp. This also doesn’t happen to everyone, so the likelihood is that an increase in DHT will only cause hair loss in people who are genetically predisposed to be more sensitive to it.⁸ 

Treatments for hair loss

You may find various online products that claim to relieve hair loss and/or promote hair growth. Though overall, the level of evidence to support these products is limited. There are, however, two approved treatments for androgenic alopecia, which are applied topically or taken orally, and work by increasing blood flow to the hair follicles, and stopping the conversion of testosterone to DHT.

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References  

1. Handelsman DJ. Androgen Physiology, Pharmacology, Use and Misuse: Endotext 2020. Available at: https://www.ncbi.nlm.nih.gov/books/NBK279000/#_NBK279000_pubdet_.  

2. Nassar GN, et al. StatPearls: Physiology 2022; available at: https://www.ncbi.nlm.nih.gov/books/NBK526128/.    

3. Miranda BH, et al. FASEB J 2018;32(2):795–806.  

4. Hamilton J B. The Biology of Hair Growth 1958:399–433.  

5. Randall V. A. (2007) Hormonal regulation of hair follicles exhibits a biological paradox. Semin. Cell Dev. Biol. 18, 274–285.  

6. Randall V. A. (2008) Androgens and hair growth. Dermatol. Ther. (Heidelb.) 21, 314–328.  

7. Hackett G, et al. J Sex Med. 2017;14(12):1504-1523.  

8. Ustuner, E. Plast Reconstr Surg Glob Open 2013; 1(7).