Men who have sex with men (MSM)

Men who have sex with men (MSM), are male persons who engage in sexual activity with members of the same sex.

They may identify as gay, homosexual, bisexual, pansexual, or heterosexual.

MSM refers to sexual activities between men, regardless of how they identify, whereas gay can include those activities but is more broadly seen as a cultural identity. 

Homosexuality refers to sexual/romantic attraction between members of the same sex and may or may not include romantic relationships. 

Gay is a social identity and is generally the preferred social term, whereas homosexual is used in formal contexts, though the terms are not entirely interchangeable.

Worldwide, at least 3% of men have had sex at least once with a man.

In the U.S., among men aged 15 to 44, an estimated 6% have engaged in oral or anal sex with another man at some point in their lives, and about 2.9% have had at least one male sexual partner in the previous 12 months.

Many MSM do not engage in anal sex, and may engage in oral sex, frotting or mutual masturbation instead.

Among men who have anal sex with other men, the insertive partner may be referred to as the top, the one being penetrated may be referred to as the bottom, and those who enjoy either role may be referred to as versatile.

Before the AIDS pandemic, 

around 28% of male homosexuals reported having more than 1000 partners and only 26% reported having less than 100 partners.

Among men who have anal sex with other men, anal sex without use of a condom is considered to be high-risk for STI transmission. 

Sexually transmitted diseases (STDS/STIs) can enter through the urethra or through small cuts, abrasions, or open sores on the penis. 

Worldwide, an estimated 5–10% of HIV infections are the result of men having sex with men.

In the United States, men who have had sex with men have an HIV prevalence 60 times higher than the general population.

MSM  is only 2% of the U.S. population but account for 53% of the overall diagnoses and 71% of cases among men with HIV.

In a 2010 federal study, one in five men who have sex with men are HIV positive and nearly half do not realize it.

HIV prevalence in the MSM population of the U.S. varies widely by ethnicity.

As many as 46% of black MSM have HIV while the HIV rate is estimated at 21% for white MSM and 17% for Hispanic MSM.

HIV infection is increasing at a rate of 12% annually among 13–24-year-old American men who have sex with men.

Pre-exposure prophylaxis (PrEP)  has been shown to be highly effective, reducing the risk of contracting HIV up to 99%.

Men who have sex with men are at a higher risk of acquiring hepatitis B and hepatitis A.

Hepatitis A and hepatitis B vaccination are recommended for men who have sex with men.

Syphilis transmission occurs during vaginal, anal, or oral sex.

Genital human papillomavirus (HPV) is a common virus that most sexually active people have at some point.

HPV is passed on through genital contact and is also found on areas that condoms do not cover.

MSM and men with compromised immune systems are more likely than other men to develop anal cancer.

The incidence of anal cancer among HIV positive MSM is nine times higher than among HIV‐negative MSM, even with  antiretroviral therapy. 

Men with HIV are also more likely to get severe cases of genital warts that are hard to treat.

Giardiasis can be transmitted between gay men, and it can be responsible for weight loss and death for individuals who have compromised immune systems, especially HIV.

The majority of gay and bisexual men have and maintain good mental health.

MSM are at greater risk for mental health problems. 

Stigma and homophobia can have negative consequences on health. 

Gay and bisexual men have a higher chance of having depression and anxiety disorders.

Many countries impose restrictions on donating blood for men who have or have had sex with men, as well as their female sexual partners.

Substance use across a wide range of substances is higher among gay, bisexual and other men who have sex with men than among men who do not have sex with men.

Drug use disorders among  MSM are 2.4-2.8 times as common as among other men.

The combined incidence of gonorrhea, chlamydia, and syphilis was lower by 2/3 with doxycycline post exposure prophylaxis than with standard care, supporting its use among MSM with recent bacterial STI’s.