The Link Between HIV and STDs

How Infections Like Gonorrhea and Syphilis Can Increase the Risk of HIV

CC license at
Wesley Wilson

It is generally accepted as a rule that having a sexually transmitted disease (STD) increases in a person's risk of getting HIV, both for biological and behavioral reasons. According to research, STDs like syphilis and gonorrhea not only provide HIV easier access to vulnerable cells and tissues of the body, STD co-infection actually increases the infectivity of the person with HIV—making them more likely to transmit the virus to others.

STDs can increase HIV susceptibility in a number of ways:

  • Some STDs cause open wounds or ulcers to form in the genital area (such as syphilis, which frequently presents with ulcerative chancres). These wounds, sometimes seen and sometimes not, provide HIV a direct route into the bloodstream.
  • While some STDs don't cause open wounds, the presence of the infection can cause the body to increase the concentration of  CD4 T-cells in the genital area. It has been well established that increased concentrations these cells can provide HIV with a favorable target for infection.
  • People infected with an STD also have increased concentrations of HIV in their seminal and vaginal fluids, increasing the possibility of HIV transmission. One study showed that men infected with HIV and gonorrhea have 10 times more HIV in their semen than men infected only with HIV.

Prime among the concerns are STDs like infective syphilis, gonorrhea, and herpes (HSV), with evidence that chlamydia can also increase HIV risk in women.

The Benefits of STD Screening and Treatment

In the presence of an STD diagnosis, people should receive treatment as soon as possible—not only to treat the infection but to potentially decrease the risk of onward transmission should you have HIV.

According to the latest research, HIV-positive people on STD therapy tend to shed far less HIV and to shed the virus less frequently than those not on treatment.

(Shedding is the state where the HIV is present in semen, vaginal secretions, blood, or breast milk even when a person has an undetectable HIV viral load).

Additionally, safer sex counseling hand-in-hand with STD therapy can help a person uninfected by HIV to identify their personal risk factors and find ways to better reduce their risk of HIV.

Take-Home Points

Oftentimes, we tend to focus on HIV in isolation, particularly when it comes to issues of prevention and treatment. But the fact is this: even if a person is on the HIV prevention pill (PrEP) or is taking full-time antitretroviral therapy, STDs can increase the risk of HIV transmission, putting yourself or others at risk.

It is, therefore, important to remember the following take-home points:

  • An HIV-negative person with an STD has a greater chance of getting HIV.
  • The presence of STD in a person with HIV can increase that person's chance of spreading the virus.
  • STD treatment may help slow the spread of HIV.
  • HIV therapy does nothing to reduce your risk of acquiring another type of STD.
  • Condoms are still the best means to reduce the risk of getting an STD, including HIV.


Fleming, D. and Wasserheit, J. " From epidemiological synergy to public health policy and practice: The contribution of other sexually transmitted diseases to sexual transmission of HIV infection." Sexually Transmitted Infections. 1999; 75:3-17.

Pathela, P.;  Braunstein, S.; Schillinger, J.; et al.  "Men who have sex with men have a 140-fold higher risk for newly diagnosed HIV and syphilis compared with heterosexual men in New York City."  Journal of Acquired Immune Deficiency Syndrome. 2011; 58:408-416.

Peterman, T.; Newman, D.; Maddox, L; et al.  "Risk for HIV following a diagnosis of syphilis, gonorrhoea or chlamydia:  328,456 women in Florida, 2000–2011."  International Journal of STD and AIDS. 2014; published online 8 April DOI: 10.1177/0956462414531243.

Freeman, E.; Weiss, H.: Glynn, J.; et al.  "Herpes simplex virus 2 infection increases HIV acquisition in men and women: systematic review and meta-analysis of longitudinal studies." AIDS. 2006; 20:73-83.