Does Cannabis cause gynecomastia? The simple answer is not 100% conclusively, but there is a very strong connection.

does cannabis cause gynecomastia

A man holding a cannabis joint in San Francisco

In simple terms, gynecomastia is the enlargement of male breast tissue and often referred to as man-boobs or moobs for short. Male breast enlargement occurs due to an imbalance in the hormone levels of testosterone and estrogen. When the male hormone testosterone ratio decreases compared to that of the predominantly female hormone estrogen, then the body signals for creating excessive breast tissue in males. 

What is the Active Ingredient in Cannabis?

The active ingredient in cannabis, tetrahydrocannabinol (THC), has been shown to reduce the level of testosterone in animal studies. The fall in testosterone is due to the effect of this THC in lowering the serum testosterone levels. THC can alter neural transmitters of the hypothalamus or that of CNS neural transmitters. Therefore, there is a reduction in testosterone produced by the testis’ Leydig cells (Harclerode, 1984).

Scientific Articles Investigating, Does Cannabis cause Man-boobs?

Although animal studies have shown an association, studies in humans have not conclusively demonstrated that Pot causes gynecomastia. A clinical study conducted on U.S. army soldiers found no significant difference between cannabis users and controls (Cates & Pope, 1977). 

In another human study, 1215 healthy men Dutchmen between the ages of 18 and 28 were evaluated for Pot induced gynecomastia between 2008 to 2012. The study showed that regular marijuana users had a reduced sperm concentration by 52%, and total sperm count by 55% (Gundersen, et al, 2015). 

Cuhaci et al. (2014) has shown that cannabis use can lead to the development of male breast tissue or gynecomastia; however, the mechanism by which it happens is not very clear. Nordt & DiVasta (2008) have shown that it is essential to inquire if they have a history of illegal drug usage when examining adolescents with gynecomastia.

Clinical Observation by Man-boobs Specialist

Dr. Steven Goldman, a plastic surgeon, has claimed that boys who are regular users of cannabis in their formative years, had a higher probability of developing man boobs later in life (Huffpost, Jan 2014). The transient effect of breast enlargement, which is seen in some boys reaching puberty, can become permanent due to pot use as their testosterone levels are altered by marijuana. Cannabis interferes with the healthy development in teen males, and it can lead to excessive breast tissue even after puberty than others who do not use it. Yet another plastic surgeon from Pennsylvania, Dr. Adrian Lo, who specializes in reducing male breast size, has stated that one-third of his male patients are frequent pot users (Huffpost, Jan 2014). Another gynecomastia specialist, Miguel Delgado, MD, has treated several thousand men with gynecomastia. He has observed a clear connection between Pot usage and gynecomastia. He states that it doesn’t affect all men, in the same way, and that the effect is dose-related or how much cannabis a person smokes. Also, when they start to smoke, rather it is during puberty or later in life.

With the state of Colorado legalized cannabis in 2012, there has been a boom in recreational marijuana. Legalization of Pot has led to an increase in the cases of male enlargement of breasts among 18-year-olds to 35 years olds. The number of plastic surgery cases has seen a jump by 8% in this state due to man-boobs (Grosman Capraro, 2019).  

Which States that have Legalized Pot?

The recreational use of Pot or cannabis is legal in 11 states in the United States. The States include Alaska, California, Colorado, Illinois, Maine, Massachusetts, Michigan, Nevada, Oregon, Vermont, and Washington. So, over time we will see what legalization of Pot has on the increase in gynecomastia cases.


Even though there is not 100% conclusive evidence, it is clear that there is a connection between Pot and man-boobs. We have present scientific articles and clinical observation by gynecomastia experts. We have also presented the spike is gynecomastia cases since Colorado legalized marijuana. More studies are needed, and with 11 States in the U.S. having legalized Pot, we will have more valuable information in the future.


Cates Jr, W., & Pope, J. N. (1977). Gynecomastia and cannabis smoking: a nonassociation among U.S. Army soldiers. The American Journal of Surgery134(5), 613-615.

Cuhaci, N., Polat, S. B., Evranos, B., Ersoy, R., & Cakir, B. (2014). Gynecomastia: clinical evaluation and management. Indian journal of endocrinology and metabolism18(2), 150.

Gundersen, T. D., Jørgensen, N., Andersson, A. M., Bang, A. K., Nordkap, L., Skakkebæk, N. E., … & Jensen, T. K. (2015). Association between use of marijuana and male reproductive hormones and semen quality: a study among 1,215 healthy young men. American journal of epidemiology182(6), 473-481.

(Grosman Capraro Plastic Surgery, 2019)

Harclerode, J. (1984). Endocrine effects of marijuana in the male: preclinical studies. NIDA Res. Monogr44, 46-64.

Huffpost (Jan 2014) retrieved from

Nordt, C. A., & DiVasta, A. D. (2008). Gynecomastia in adolescents. Current opinion in pediatrics20(4), 375-382.


Dr. Delgado Bio


Dr. Delgado, MD is a world-recognized plastic surgeon and specialist in the treatment of male breast enlargement, also called gynecomastia. He has developed new techniques and owns and operates, which has become the largest gynecomastia forum in the world. Dr. Delgado holds the two most coveted credentials; the certification by the American Board of Plastic Surgery and membership in the American Society of Plastic Surgery.