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An illustration of a hand holding different forms of birth control

Illustration by Marta Pucci

Sex

Birth control and STI risk

by Nicole Telfer, Science Content Producer
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Top things to know:

  • External (male) and internal (female) condoms are the only forms of birth control that also protect against sexually transmitted infections (STIs).
  • Spermicides, either alone or with condoms, should probably not be used by people who are at high risk of contracting STIs. Some spermicide may cause genital irritation that increases the likelihood of transmission.
  • Progestin, the synthetic progesterone in birth control methods, may possibly decrease the risk of getting some STIs, while increasing the risk of others.

What are STIs?

STIs are illnesses that are passed through sexual contact. Sometimes they are called sexually transmitted diseases (STDs). STIs include:

STIs can be passed through any type of sex which involves the exchange of sexual fluids or genital contact, such as vaginal, anal, and oral sex.

Some STIs, like chlamydia, are curable. Others, like HIV and herpes, are lifelong infections, though people can be treated to reduce the severity of symptoms.

STIs may or may not have obvious symptoms, but even STIs without symptoms can temporarily or permanently damage a person’s body. Gonorrhea and chlamydia can affect the function of a person’s reproductive system and urinary tract, causing symptoms like discomfort while peeing (1-3). They can also cause Pelvic Inflammatory Disease (PID), which can damage the reproductive system and make it difficult or impossible for a person to get pregnant (1-4). HPV can lead to cancer (5), and untreated HIV and syphilis can lead to sickness and death (2,6).

STI transmission is not just a risk to the people having sex. Some STIs, like HIV, can be passed from mother to baby.

The choices anyone makes about their health can impact a person’s future. It’s important to take care of your body and the body of your partners. Because STIs may not have obvious symptoms (2,5,6), the only way to know that you don’t have an STI is for your and your partners to be tested.

Can birth control impact your risk of STIs?

Some methods, like condoms, have pretty well-established effects on STI transmission. Other methods, like progestin-only methods, are less studied and may have different associations depending on the STI.

Here’s what the research says about each birth control type and STI risk.

Condoms and dental dams (barrier methods)

Since STIs can be spread through direct sexual contact or exchange of bodily fluids, using a barrier method (like a condom, internal condom, or dental dam) can reduce the risk of STI transmission.

Consistent and correct use of external or internal condoms is associated with a significant reduction STIs acquisition (7,8). If you have penis-in-vagina sex with a condom, you are up to 80% less likely to contract HIV, compared to sex without a condom (9,10).

Herpes, HPV, and genital ulcer diseases like syphilis and chancroid are spread via skin-to-skin contact. If a condom does not cover the infected area, then a condom cannot offer protection from these STIs. However, if the infections are limited to areas where the condom covers, then the risk of spreading these diseases will be reduced (11).

Preventing re-exposure

Preventing the exposure of STIs through condom use may also help people who are already infected, specifically with certain HPV strains (12). In one study of people with cervical precancerous changes, condom use was shown to help the body clear the HPV infection and regression of precancerous changes, possibly by minimizing re-exposure to HPV during sexual encounters (12).

Be sure to use a condom correctly

Using condoms is an excellent way to decrease the risk of transmitting STIs, but you need to use condoms correctly and consistently to get the most benefit. To use a condom correctly, you need to follow the instructions on the box and/or from a healthcare provider (which can be quite different from how people actually use condoms).

For maximum benefit, you need to use a condom every time you have sex, and the condom should be applied correctly before any sexual contact between the genitals takes place.

We have instructions for putting on a condom here.

If a person uses a condom incorrectly—there are many reasons, but perhaps they put the condom on the wrong way, or maybe only use condoms with certain partners, or only during certain types of sex—they are at increased risk of contracting an STI.

Spermicides, hormonal birth control, and intrauterine devices (IUDs)

Use of spermicides, hormonal methods, and intrauterine devices may also increase or decrease a person’s risk of getting an STI, but most evidence of this is still in the early stages or unclear. More research and larger studies in the future will help address these questions, but below we’ve summarized what research has found so far.

Out of all of the STIs, HIV is by far the most studied, as close to 37 million people currently are infected with the disease (13). This is why lots of risks mentioned in the article focus on HIV, instead of the more common STIs in the United States and Europe, like chlamydia and gonorrhea (14,15).

Spermicides & microbicides and STIs

The chemical nonoxynol-9 is a spermicide that can be used in gels, suppositories, and as an additive to some condoms (16). Nonoxynol-9 also has microbicide abilities.

Microbicides are medications (gels, creams, suppositories) that can be inserted into the vagina or anus to theoretically prevent or decrease the risk of spreading STIs, like HIV (16,17).

However, the spermicide nonoxynol-9 should not be used by people who have a high risk of contracting HIV. This spermicide may actually increase the risk of HIV transmission by causing trauma and abrasions (16,18,19).

Current research does not support the use of any microbicides (20,12), including nonoxynol-9, to prevent HIV (22) and STIs (23), though there are preliminary studies that show some effect against HIV and HSV-2 (21,24). More research is needed to develop microbicides and other ways to prevent spreading STIs (20).

People not at high-risk of HIV can safely use spermicides alone or in conjunction with another method to reduce the risk of pregnancy, though some people may experience a reaction or irritation (25).

Combined oral contraceptives (hormonal birth control pill) and STIs

So far, research shows that using combined oral contraceptives (“the pill”) does not speed up HIV disease progression (26,27), nor does it affect HIV transmission rates from women to men having penis-in-vagina sex (26). They are considered safe for HIV positive people to use.

IUDs (copper and hormonal) and STIs

An intrauterine device (IUD) is a form of long acting birth control (LARC). There are hormonal IUDs, like the Mirena IUD, and copper IUDs, like the Paragard IUD.

IUD insertion and pelvic inflammatory disease An IUD is inserted through the opening of the cervix and placed (or sometimes attached) into the uterus by a healthcare practitioner.

Some STIs, like gonorrhea and chlamydia, can cause an infection of the cervix. If a person has a cervix that is visibly infected with an STI or inflamed (28), the United States’ Center for Disease Control and Prevention (CDC) does not recommend inserting an intrauterine device (IUD) until the infection is treated, as it may increase the risk of pelvic inflammatory disease (PID) (28).

If a person doesn’t have visible symptoms of these infections, they may be less at risk. Researchers have studied people who got an IUD inserted while they had an asymptomatic chlamydial or gonorrheal infection, or who are at higher risk of STIs. They found that people with asymptomatic infections who got an IUD inserted were no more likely to develop PID compared to people who were using another form of contraception (29).

This research helps to show that an IUD insertion does not make a person more susceptible to developing pelvic inflammatory disease among asymptomatic people (19,29), and that screening for STIs can be done at the same appointment as IUD insertion—no need to delay if there are no active markers of infection (28).

IUDs, implants, and condom use Users of some contraceptives may be more or less likely to use condoms.

In one study, people using long acting reversible contraceptives (LARC), like IUDs and implants, were half as likely to consistently use condoms when having sex, compared to people who were using other forms of birth control, though the overall rate of consistent condom use was low among across both groups (6.4%) (30).

When comparing STI rates, LARC users had double the incidence of reported STIs (3.9%) compared to non-LARC users (2.0%) (30). This reiterates the importance of consistent condom use to protect against STIs, regardless of which birth control you use.

Progestin-only birth control and STIs

Progestin, the synthetic progesterone in birth control methods, may possibly decrease the risk of getting some STIs, while increasing the risk of others.

The evidence is a little conflicting, and the increase or decrease in risk is probably associated with both the type of STI and the type of progestin.

Does progestin decrease risk of STIs? It has been suggested that progestin, the synthetic progesterone in hormonal birth control, might protect against pelvic inflammatory disease. In one study comparing a large group of women who were randomly given a hormonal IUD or a copper IUD, the hormonal IUD group had significantly fewer cases of pelvic inflammatory disease (31). Progestin thickens cervical mucus, and so researchers hypothesize that this thickening prevents STIs from entering the cervix (19,31). While these results are interesting, only one study has been conducted, and more research is needed to confirm these results.

Does progestin increase risk? In contrast, there are some theoretical reasons why hormonal contraceptives, particularly the contraceptive injectable (‘the shot”), may be associated with increased risk of HIV (32). The evidence is not considered very strong (32,33,34). More research is needed in this area.

The World Health Organization (WHO) and U.S. CDC says that the advantages of injectables for preventing unwanted pregnancy outweigh the potentially increased risk of acquiring HIV. This means that people who are at high risk of contracting HIV can still use progestin-only injections, but they need to be informed that they may be at increased risk of HIV contraction. Other forms of hormonal contraceptives are considered safe to use by the WHO and CDC without restrictions for people who are at high risk of contracting HIV (33,34).

Wrapping it all up

Even if you are happy and confident with your hormonal contraception, condoms and barrier methods are the best way to prevent the spread of STIs.

Download Clue to track sex, both with a condom (protected) and without (unprotected).

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