Receiving oral sex (i.e. having your partner suck your penis or lick/kiss your vagina/clitoris), carries NO risk of HIV transmission.  Performing oral sex (i.e.  licking/kissing a vagina/clitoris or giving a blow job/sucking a penis) is extremely low risk in terms of HIV transmission.  There are a few case reports and individual experiences that support getting HIV from performing oral sex on a penis, but it’s extremely rare. As far as whether oral sex is riskier if you swallow semen, truthfully no one really knows. Having bleeding gums, recent dental work or large sores in your mouth may slightly increase the risk.

Other STIs like syphilis, gonorrhea, chlamydia, herpes, and HPV are transmitted through oral sex. Many of these infections are easily diagnosed with simple tests and can be treated with available medications. If you are worried about your risk for HIV or STIs, talk to your health care provider about getting tested and ask them if PrEP (pre-exposure prophylaxis) makes sense for you.

Giving head (i.e. performing oral sex, giving a blow job) can put you at risk for chlamydia, gonorrhea, herpes, syphilis and possibly HPV. Getting HIV from giving head is extremely rare. 

It can take several days or up to several months to show symptoms of STIs. STIs in the back of the throat often have no symptoms and some clear on their own. A throat swab for gonorrhea and chlamydia and blood test for syphilis can tell if you have an infection. Because most STIs have no symptoms, the only way to know for sure is to get tested.  Sexually active gay men should get screened for STIs and HIV every 3 months If you're concerned about your HIV risk, talk to your provider about whether PrEP (pre-exposure prophylaxis) makes sense for you. 

We know that oral sex does carry risk for STI transmission. The risks vary depending on which infection we are discussing.

Some STIs are transmitted through skin-to-skin contact, including oral-genital and oral-anal contact. For example, herpes and syphilis are spread by contact with infectious sores or lesions, so oral sex could definitely spread these infections regardless of ejaculation. HPV can also be spread from genitals to mouth, or from mouth to mouth (http://cebp.aacrjournals.org/content/23/12/2959). Ejaculation during oral sex makes no difference with any of these infections.

Many people believe that gonorrhea and chlamydia can only be transmitted if ejaculation happens, but this is not true. The infections live in the epithelium (skin cells) of mucous membranes, like the cells lining the urethra (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC523569/ and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4886739/). The bacteria are present on these cells, and can be transferred to the throat without ejaculate (cum) or even pre-ejaculate (pre-cum) being present. Interestingly, one study (https://sti.bmj.com/content/93/2/88) showed that gargling with Listerine reduced the amount of gonorrhea bacteria in the throat, but this study didn’t follow up to find out if this means fewer cases of gonorrhea were transmitted from throat to genitals.

Oral sex with or without swallowing semen both carry a very low risk of HIV infection – so low that we cannot calculate an accurate number (https://www.cdc.gov/hiv/risk/estimates/riskbehaviors.html).  We do not have any studies that look specifically at the difference in risk without ejaculation.If you are concerned about the low risk of HIV transmission via oral sex, you could communicate this to partners and then not swallow any semen that is present. From a harm reduction perspective, this may be less risky, but we just don’t have any scientific proof to say for sure if swallowing makes a difference.

We recommend that sexually active gay men and other men who have sex with men be tested for HIV and STIs (gonorrhea, chlamydia, and syphilis) every three months. Testing for syphilis usually involves a quick physical exam and a blood test. Testing for gonorrhea and chlamydia involves a urine sample if you perform insertive oral sex or anal sex (i.e. if you “top”), a swab of your throat if you perform oral sex on other guys, and a rectal swab if you practice receptive anal sex (i.e. if you “bottom”).  If you are not getting tested every three months ask your provider if you can be. You can ask your provider what your syphilis infection status is; whether you have gonorrhea or chlamydia in your butt, throat or penis; and talk with your provider about ways to reduce your risk for getting STIs and HIV. If you're not on PrEP, you could talk with your provider about whether PrEP makes sense for you.  

There are a number of vaccines that can protect you against STIs - ask your provider if you need vaccines against Hepatitis A, Hepatitis B, HPV or meningococcus. You should also ask about anal cancer screening and your risks; and what warts look like and how they are treated.  Your provider should be thinking about all aspects of your health including use of tobacco, alcohol and recreational drugs; and what you do for exercise and your diet.

This means that you were infected with hepatitis C at some point but your body was able to clear (get rid of) the infection, and so you no longer have the virus. Unfortunately, if you are exposed to hepatitis C in the future, you can be re-infected.

Some people never clear hepatitis C and so the virus is still detectable in their blood. This means they are at risk for the complications of having hepatitis C, for instance iver damage, and that they can transmit it to others. Luckily there are well tolerated medications that can treat hepatitis C in as little as 8-12 weeks.

It is definitely possible to spread herpes from one partner’s mouth to another partner’s genitals during oral sex, which would result in the uninfected partner contracting genital HSV-1. Transmission is more likely when sores are present, but sometimes herpes can be transmitted without any symptoms – we call this “asymptomatic viral shedding.” This shedding can happen in both oral and genital herpes infections. Shedding is most common in the first few months after getting a new infection, and the frequency of shedding depends on which type of HSV you have and where the infection is. For example, oral HSV-1 (what we call “cold sores”) sheds about 12% of days, and genital HSV-2 sheds about 20% of days (https://academic.oup.com/jid/article/198/8/1098/879583). Another study showed shedding of genital HSV-2 on 10% of days (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3144252/). Since this shedding is invisible, its not possible to know for sure when your partner is potentially contagious.

Even though your partner has herpes, it is not a guarantee that you will contract the infection. One study showed that transmission between couples is about 10% per year, and about 70% of these transmissions happened when the infected partner had no symptoms (https://annals.org/aim/article-abstract/705283/risk-factors-sexual-transmission-genital-herpes?volume=116&issue=3&page=197).

Avoiding contact with visible sores will reduce your risk of getting oral HSV-1 when your partner goes down on you.

At City Clinic, we perform herpes tests by swabbing sores. This is the most accurate way to test, and this kind of test can distinguish between HSV-1 and HSV-2. There are blood tests available, but we do not routinely use these for our visits. City Clinic does not have blood tests for HSV-1 – if you would like this test, please talk with your primary care provider.

It is definitely possible that you have genital herpes and that your partner does not. Only your partner knows for sure if he is telling the truth, but here are some scenarios in which he could be correct about not having herpes when you do. One possibility is that you have had herpes for a long time and were just recently diagnosed. Many people with genital herpes are unaware that they are infected and find out when they get a positive blood test for herpes, or when they develop symptoms of an outbreak. It can be very hard to accurately determine when you contracted a herpes infection. The only way to prove that your current outbreak is new is to have a swab test of the genital lesions turn out positive right now, and a blood test for the same type of herpes be negative right now. If a second blood test a few months later turns out positive it would confirm that this is a new infection, since blood tests take a few months after a first herpes outbreak to turn positive. If your herpes blood test is positive at the time of your first outbreak, this tells us that you have had that type of herpes for at least a couple of months, but we cannot be any more specific about when you first got the infection. It is also possible that your partner does have herpes and had a false negative test. Herpes blood tests can be negative even though someone is actually infected. This is most common in the first few weeks after infection, before the body has produced antibodies to the virus – the blood test is looking for these antibodies, so the blood test can be negative during the first few weeks after someone has been infected with herpes. Additionally, herpes does not transmit 100% of the time. It’s possible to have a long-term partner who has herpes and to never get the infection.

If your partner does not have herpes, there are some things for you both to know to move forward. If you have herpes, it is not a guarantee that you will give the infection to your partner. One study showed that transmission between couples is about 10% per year, and about 70% of these transmissions happened when the infected partner had no symptoms (https://annals.org/aim/article-abstract/705283/risk-factors-sexual-transmission-genital-herpes?volume=116&issue=3&page=197).

Condom use can reduce (but not eliminate) the risk of transmission. One study showed that using condoms most of the time reduces transmission from an infected man to an uninfected woman (https://jamanetwork.com/journals/jama/fullarticle/193953) – though this study only looked at monogamous heterosexual couples. Another study analyzed multiple other studies and found that people who use condoms every time they have sex have a much lower risk of contracting HSV from an infected partner (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2860381/).

Daily medication (using either acyclovir or valacyclovir) can reduce the risk of you spreading the infection to a partner. One study of people with genital HSV-2 who took a daily antiviral medication showed that people taking medication were both less likely to shed virus, and less likely to transmit the virus to their partners (https://www.nejm.org/doi/10.1056/NEJMoa035144?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dwww.ncbi.nlm.nih.gov). In addition, people who both took daily medication and used condoms for intercourse had no cases of herpes transmission in this study.

With herpes, as with any STI, a diagnosis shouldn't be about the blame game. What it should be about is good communication between you and your partner(s), education about the disease and the best way to stay healthy, and limiting transmission to others in the future. Herpes is incredibly common, but very manageable.

Though it can be difficult, it is recommended to discuss a herpes diagnosis with a potential sex partner. Doing so can set the relationship off on the right foot and allow both of you to be involved in a conversation about prevention strategies. For a great resource for talking with partners about a herpes diagnosis, check out: https://www.ashasexualhealth.org/herpes-and-relationships/.

For more information about herpes go to herpes STI basics.

Genital herpes is common. It is usually caused by HSV-2, but it can also be caused by HSV-1. About 12% of people in the US have been infected with HSV-2. Its possible you've been infected with HSV-2 in the past and don't know it, because not everyone who gets infected with HSV-2 develops symptoms (for example, ulcers or an ""outbreak""). You could ask your primary care provider to test you for antibodies to HSV-2, this would tell you whether or not you've already been infected.

If you've already been infected with HSV-2 in the past, then your partner can’t transmit to it you. If you have not been infected with HSV-2, then there are a few things you can do to protect yourself. Condoms reduce the chances of HSV transmission by about 50%. Another way to prevent HSV-2 transmission is for your partner to take a daily anti-HSV medication (like acyclovir or valacyclovir). This will reduce the chance that your partner will pass HSV-2 on to you. For more info about herpes, look here and to http://www.ashasexualhealth.org/stdsstis/herpes/

One study of people with genital HSV-2 who took a daily antiviral medication showed that people taking medication were both less likely to shed virus, and less likely to transmit the virus to their partners. In addition, people who both took daily medication and used condoms for intercourse had further reduced risk of herpes transmission in this study.

The CDC recommends that all adults > 18 years old are tested for HIV at least once in their lifetime. Men who have sex with men, trans people who have sex with men and people who inject drugs should be tested more frequently. In San Francisco, we recommend that folks in these groups get tested for HIV every 3 months. People on PrEP should also get tested for HIV every 3 months.

We recommend that you talk with your healthcare provider about your sexual and drug use practices. This will help your provider determine what tests you need and how often you should be tested. Testing recommendations depend on your situation, for instance if you or your partner use drugs (like methamphetamine or cocaine), if you're experiencing homelessness, have a history of incarceration, have a history of an STI, do sex work, or if you think your partner may be having other partners.