Patient information: Preventing HIV after unprotected sex or needle-sharing (The Basics)
23/12/15 8:30
Official reprint from UpToDate® www.uptodate.com ©2015 UpToDate®
Patient information: Preventing HIV after unprotected sex or needle-sharing (The Basics) Written by the doctors and editors at UpToDate How do you catch HIV from someone who is infected? — You can catch HIV from someone who is infected if you: ● Share the same needle, for example to inject drugs ● Have anal, vaginal, or oral sex with them If you get blood or other body fluids in your vagina, anus, or inside the tip of your penis, you could get infected. It is also possible to get infected if blood or fluids with HIV get into your eyes or mouth, but this is less risky. It is very unlikely that you would catch HIV just by getting blood or other body fluids on your skin. Body fluids that are most dangerous include blood and the fluids that come from the penis, vagina, and anus during sex. Other body fluids are less dangerous, as long as they aren’t mixed with blood. This includes urine, saliva, sweat, or tears. Human bites are unusual, but HIV can be passed from one person to another if one of them is infected, and the bite breaks the skin. Can I lower my chances of getting HIV even after being exposed to the virus? — In some cases, yes. There are treatments that can reduce your risk of getting HIV (called “preventive medicines”), but you must start them within 3 days of being exposed to the virus. If you think you have been exposed to HIV, see your doctor or nurse right away. If an unusual event happened, like a condom broke, or you had unprotected sex, or you were raped, taking medicines after the event might help you. You should keep in mind that the risk of getting HIV after one exposure is usually pretty low. Still, it is always best to discuss your risk of HIV with your doctor or nurse. He or she can give you the best advice after an exposure. Don’t try to figure out your risk of HIV on your own. You should also keep in mind that medicines to prevent HIV after exposure are not for people who risk getting exposed over and over again. In other words, if you commonly have unprotected sex or use dirty needles, these treatments are not for you. Instead, you might be able to take HIV medicines every day to reduce the risk of getting HIV. If you do this, it is very important to always remember to take the medicines and visit your doctor regularly. Ask your doctor if this treatment is right for you. How likely is it that I will catch HIV? — That depends on a lot of factors, such as: ● How you were exposed – Some ways of getting exposed are riskier than others. For example, although it is possible to catch HIV through oral sex, it is unusual. On the other hand, sharing dirty needles is extremely risky. Also, anal sex is riskier than vaginal sex. ● Whether you have any sores or cuts on the part of your body that was exposed – People who have open wounds or sores are more likely to get infected. For example, if you have herpes sores on your genitals, your risk of catching HIV goes up. ● Whether the body fluids you were exposed to came from a person who actually has HIV – If the person has HIV but is being treated, your risk will be low. If the person has HIV and has a lot of virus in his or her blood, your risk of getting HIV goes up.
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Patient information: Preventing HIV after unprotected sex or needle-sharing (The Basics)
23/12/15 8:30
What will the doctor or nurse do? — First, your doctor or nurse will probably test you for HIV. This will tell him or her whether you were already infected with the virus in the past. If so, it won't make sense to give you medicine to prevent HIV infection. Then your doctor or nurse will talk to you about the chances that you could get infected, and what you can do about it. You and your doctor will have to decide if HIV medicines are right for you based on how likely it is that you could become infected, and on how you feel about the risks and benefits of taking medicines. If the two of you decide that you should take medicines to prevent HIV infection, your doctor or nurse will usually prescribe 3 different medicines. You will need to start these as soon as possible and take them for a month. If the person who exposed you is willing to be tested, your doctor or nurse might test him or her also. If the person who exposed you doesn’t have HIV, then you won’t have to take HIV medicines. Your doctor might also test or treat you for other types of infections you can catch through sex or by sharing needles. What are the risks or side effects of medicines to prevent HIV? — The side effects differ depending on which specific medicines you take. Ask your doctor which side effects to expect and what to do about them. If you are pregnant or could be pregnant, tell your doctor or nurse. Some medicines are not safe to use in pregnant women, so your doctor or nurse needs to know if you are or could be pregnant. What happens after I am done taking the medicines? — Your doctor or nurse will test you again to see if you got infected with HIV. These tests will be done at 6 weeks, 3 months, and 6 months after your exposure. If you are a woman, your doctor will check to make sure you did not get pregnant. It is very important that you take all the medicine your doctor prescribes. Still, even if you take all your medicine as directed, there is no guarantee that you will not get infected. The medicines improve your chances, but they do not always prevent infection. That is why it is best not to share needles or have unprotected sex in the first place. In the weeks after your exposure, look for symptoms of HIV infection, such as: ● Fever ● Swollen glands ● Sore throat ● Sores in your mouth, penis, anus, or vagina ● Muscle and joint pain ● Diarrhea ● Headache ● Nausea or vomiting ● Weight loss If you notice any symptoms that worry you, call your doctor or nurse. What else should I do? — Until you know for sure whether you have HIV, make sure to use condoms during sex. Or avoid sex. Do not donate blood, sperm, or any tissues. Otherwise, if it turns out you did catch HIV, you could infect someone else. More on this topic Patient information: HIV/AIDS (The Basics) Patient information: Starting treatment for HIV (The Basics) Patient information: Tests to monitor HIV (The Basics) Patient information: Blood or body fluid exposure (The Basics) http://www.uptodate.com/contents/preventing-hiv-after-unprotect…icKey=PI%2F16274&elapsedTimeMs=1&view=print&displayedView=full
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Patient information: Preventing HIV after unprotected sex or needle-sharing (The Basics)
23/12/15 8:30
Patient information: Screening for sexually transmitted infections (The Basics) Patient information: Care after rape or sexual assault (The Basics) Patient information: Testing for HIV (Beyond the Basics) Patient information: Symptoms of HIV infection (Beyond the Basics) Patient information: Initial treatment of HIV (Beyond the Basics) All topics are updated as new evidence becomes available and our peer review process is complete. This topic retrieved from UpToDate on: Dec 23, 2015. The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of UpToDate content is governed by the UpToDate Terms of Use. ©2015 UpToDate, Inc. All rights reserved. Topic 16274 Version 3.0
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