Why Do Gay Men Have an Increased Risk of HIV?

Factors That Affect Men Who Have Sex With Men (MSM)

In the United States, gay men are affected by human immunodeficiency virus (HIV) more than any other people. Men who have sex with men (MSM) is a term that refers to gay men as well as those who may identify in other ways, such as bisexual or heterosexual. MSM are disproportionately at risk of acquiring HIV.

While men who have sex with men represent only 2% to 7% of the U.S. population, 70% of all new HIV infections in 2019 were in this group. One-third of these were among Black MSM.

There are many reasons for this and several risk factors unique to men who have sex with men that can compound the odds of infection. It is these overlapping risk factors that account for the high rate of HIV among this group.

This article takes a closer look at four key factors—physiological, sexual, social, and cultural—that place gay men and other men who have sex with men at the highest risk of HIV compared to all other groups.

Two men in bed

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Physiological Risk Factors

Not all men who have sex with men engage in anal sex. However, anal sex is one of the main ways MSM acquire HIV.

Unprotected anal sex, also known as condomless anal sex, is by far the most efficient means of passing the virus. In fact, condomless anal intercourse is 18 times more likely to transmit HIV than condomless vaginal sex. This is true regardless of the sex of the receptive ("bottom") partner.

One of the main reasons for this is the structure of the rectum itself. Unlike the vagina, which is lined with a dense layer of cells (called epithelial cells) that acts as a barrier, the rectum only has a single column of these cells. Because rectal tissues are fragile, they are also prone to breakage, allowing the virus to slip past this thin layer.

Rectal tissues are also rich in immune cells called CD4 T cells. These are the very cells that HIV targets for infection.

Because of this, HIV can establish an infection quickly. Studies using animal models have shown that within an hour of rectal exposure, HIV can breach the body's frontline immune defenses. Within 24 hours, the virus can spread throughout the body.

Pre-exposure prophylaxis (PrEP) is medication that is highly effective at reducing these risks. However, due to lack of awareness and access, only about one third of men who have sex with men reported using PrEP in 2017.


Condomless anal sex is one of the most common ways men who have sex with men can acquire and transmit HIV. Not only is the protective lining of the rectum thinner and more breakable than the vagina, but it is rich in the very immune cells that HIV targets for infection.

Sexual Risk Factors

Sexual practices, exposures, and partners all factor into HIV risk.

The bottom partner in anal sex is between two and 12 times more likely to get HIV than the top (insertive) partner. Those differences can all but vanish if a person is sexually versatile (able to switch between being top and bottom).

There is also a high rate of sexually transmitted infections (STIs) among men who have sex with men. Much of this has to do with a lack of inclusive sex education addressing the needs of LGBTQ+ people.

Having an STI can increase the odds of getting HIV. Some infections, like syphilis, increase the risk by as much as 500%.

Among the reasons for the high rate of STIs, men who have sex with men are more likely to have multiple sex partners (of either sex) compared to those who exclusively have sex with women.

MSM between the ages of 18 and 24 are more likely to have sex with a partner five or more years older than them. This matters in terms of their risk because the older someone is, the more sexual encounters they are likely to have had.


Men who have sex with men have higher rates of STIs and are more likely to have multiple sex partners, both of which increase the risk of HIV. Having an older sex partner and engaging in versatile anal sex also influences the risk.

Societal Risk Factors

Society also plays a role in the risk of HIV among men who have sex with men, particularly those who are Black or Latinx.

Poverty, racism, high rates of unemployment, lack of government support, and poor access to health care all contribute to the high rates of HIV in people of color. Add to that the risk factors impacting men who have sex with men in general, and it becomes clear why this group is disproportionately affected.

According to 2019 data, 76% of people living with HIV in the United States have a household income of less than $20,000 per year. Of these, 39% have no job, while 18% are homeless. People of color account for the lion's share of these numbers.

On top of that, people generally tend to have sex with their own race. Because of this, MSM of color are more likely to get HIV because their sexual networks are smaller and the rate of infection in communities of color is higher than in white communities.

These intersecting risk factors compound an already tough situation. Today, Black men who have sex with men in the United States have no less than a 50% lifetime risk of getting HIV, according to a study from the Centers for Disease Control and Prevention (CDC).


Poverty, racism, high rates of employment, and unequal access to health care amplify the risk of HIV in Black and Latinx men who have sex with men.

Cultural Risk Factors

People with HIV are frequent targets of stigma—not just because of their HIV status, but sometimes also because of their sexual orientation and race. This can affect their health in a number of ways.

Some people wrongfully believe that the high rate of HIV among men who have sex with men confirms that gay and bisexual people are "promiscuous," "diseased," or "immoral." This attitude can send many MSM into hiding.

Rather than subject themselves to shame or discrimination, some men may avoid HIV testing and treatment until the disease is advanced and harder to manage.

Testing positive may also force them to come out about how they got infected, which they may not want or be ready to do.

If they do get tested and have HIV, isolation and a lack of support—which many already know all too well—can lead to depression, alcohol or drug abuse, sexual risk-taking, and inconsistent treatment and care.

All of this accounts, at least in part, for why one of every six MSM with HIV remains undiagnosed compared to one of every eight heterosexuals with HIV.

Among Black MSM with HIV, who may be particular targets of stigma, racism, and homophobia, only 59% who get treatment remain in care. Among Latinx men who have sex with men, these same effects translate to higher rates of injecting drug use, further spreading the disease.


The fear of stigma and homophobia discourage many men who have sex with men from seeking HIV testing and treatment. Of those who test positive, isolation and a lack of support can lead to depression, substance abuse, sexual risk-taking, and inconsistent care.


Men who have sex with men (MSM) account for 2% to 7% of the U.S. population but around 70% of all new HIV infections each year. There are numerous factors that place gay and bisexual men at such high risk, including physiological vulnerabilities, sexual practices, social and economic inequities, and cultural stigma.

Black and Latinx men who have sex with men are especially impacted due to the intersection of these and other risk factors, including racism and homophobia.

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