HIV Testing

Truth about AIDS

After HIV infection occurs, it may be years before the virus destroys the immune system and serious infections and some cancers appear. At that point, the HIV infection has progressed to AIDS. New drug treatments can delay the effects of HIV/AIDS and are helping patients live longer. But the reality is that no medicine can cure AIDS or the virus that causes it, HIV. Once inside the body, HIV destroys immune system cells if not treated, with a progression to AIDS. AIDS remains a deadly epidemic worldwide.


The Stanford Positive Care & Sexual Health Clinic currently offers the ELISA, Western Blot, PCR and Genetic testing. Other types of testing include Rapid testing and Home-testing kits.

Exposure to HIV

If you have been exposed to HIV then you should call to make an appointment at the Positive Care Clinic or a surrounding health care facility so you can be counseled for PEP which is post exposure prophylaxis.

What is Post-Exposure Prophylaxis?

Post-Exposure Prophylaxis (PEP) involves taking anti-HIV medications as soon as possible after you may have been exposed to HIV to try to reduce the chance of becoming HIV positive. These medications keep HIV from making copies of itself and spreading through your body.

There are two types of PEP:

  1. Occupational PEP (sometimes called "oPEP"), taken when someone working in a healthcare setting is potentially exposed to material infected with HIV, and?
  2. Non-occupational PEP (sometimes called “nPEP”), taken when someone is potentially exposed to HIV outside the workplace (e.g., from sexual assault, or during episodes of unprotected sex or needle-sharing injection drug use).

To be effective, PEP must begin within 72 hours of exposure, before the virus has time to make too many copies of itself in your body. PEP consists of 2-3 antiretroviral medications and should be taken for 28 days. Your doctor will determine what treatment is right for you based on how you were exposed to HIV. PEP is safe but may cause side effects like nausea in some people. These side effects can be treated and are not life threatening. PEP is not 100% effective; it does not guarantee that someone exposed to HIV will not become infected with HIV.

Who Needs PEP?

PEP is used for anyone who may have been exposed to HIV during a single event.

The risk of getting HIV infection in these ways is extremely low—fewer than 1 in 100 for all exposures.

PEP can also be used to treat people who may have been exposed to HIV during a single event unrelated to work (e.g., during episodes of unprotected sex, needle-sharing injection drug use, or sexual assault).

Keep in mind that PEP should only be used in uncommon situations right after a potential HIV exposure. It is not a substitute for other proven HIV prevention methods, such as correct and consistent condom use or use of sterile injection equipment.

Because PEP is not 100% effective, you should continue to use condoms with sex partners while taking PEP and should not use injection equipment that has been used by others. This will help avoid spreading the virus to others if you become infected.

When Should I Take PEP if I've been Exposed?

To be effective, PEP must begin as soon as possible, but always within 72 hours of exposure. Your healthcare provider will consider whether PEP is right for you based on how you might have been exposed and whether you know if the person whose fluids you were exposed to might be HIV-positive. You will be asked to return for more HIV testing at 4 to 6 weeks, 3 months, and 6 months after the potential exposure to HIV. (Talk to your healthcare provider about the recommended follow-up schedule for you.)

For more information, see the Center for Disease Control and Prevention’s (CDC) Updated (2013) U.S. Public Health Service Guidelines for the Management of Occupational Exposures to Human Immunodeficiency Virus and Recommendations for Postexposure Prophylaxis (oPEP) or Nonoccupational Postexposure Prophylaxis (nPEP) Guidelines.

Who Pays for PEP?

Antiretroviral medications are expensive, and many people cannot pay for them out of pocket. If you are a healthcare worker who was exposed to HIV on the job, your workplace health insurance or workers’ compensation will usually pay for oPEP. If you are prescribed nPEP after sexual assault, you may qualify for partial or total reimbursement for medications and clinical care costs through the Office for Victims of Crime funded by the U.S. Department of Justice (see the contact information for each state). If you are prescribed nPEP for another reason, and you cannot get insurance coverage (private, employer-based, Medicaid, or Medicare), your healthcare provider can help you apply for free antiretroviral medications through the patient assistance programs of the drug manufacturers. Online applications can be faxed to the company, or some companies have special phone lines. These can be handled urgently in many cases to avoid delay in accessing medication. See information for specific medications and manufacturers.

As with many other conditions, early detection offers more options for treatment. The Stanford Positive Care Clinic offers pre-exposure prophylaxis (PEP)

What Is Pre-Exposure Prophylaxis?

PrEP stands for Pre-exposure prophylaxis. Prophylaxis means disease prevention. PrEP is a new HIV prevention option for HIV-negative individuals to reduce their risk of HIV infection. PrEP for HIV prevention is the use of antiretroviral medications (ARVs) by HIV-negative individuals to reduce risk. Large research studies showed that PrEP could help prevent new HIV infections when used by people at high risk of getting HIV.

The only good facts on PrEP are based on using the combination pill Truvada (see Fact Sheet 421) taken once a day. There is not enough information on any other dosing or other medications. We don't yet know if other drugs or dose timing (like a few times a week instead of every day) might also be a good way to reduce risk of HIV.

Truvada as PrEP was studied in people who were at high risk of HIV infection. HIV-negative men who have sex with men, transgender women, and heterosexuals at high risk were studied. Results in these studies have varied, Major studies showed that daily Truvada as PrEP can reduce risk of infection between 44% and 90%. The studies showed that PrEP worked best for people who took the medication every day.

How Is PrEP Taken?

PrEP is currently one tablet of Truvada daily. It can be taken with food, or between meals.There is research ongoing to look at other medications for PrEP.

Truvada contains two medications, tenofovir (Viread) and emtricitabine (Emtriva). Truvada is only available with a prescription.

Who Should Use PrEP?

PrEP is more than simply taking HIV pills. The US Centers for Disease Control and Prevention (CDC) has issued guidelines for the use of PrEP. One set of guidelines is for men who have sex with men. Another is for heterosexuals.

How Should People Using PrEP Be Monitored?

The CDC guidelines recommend that people taking PrEP be seen every 2-3 months in order to:

What Are the Likely Side Effects?

The most common side effects seen in the studies of Truvada as PrEP include headache, nausea, vomiting, rash and loss of appetite. In some people, tenofovir can increase creatinine and transaminases. These are enzymes related to the kidneys and liver. High levels can indicate damage to these organs. Long-term use of tenofovir can damage the kidneys.

Tenofovir can reduce bone mineral density (see Fact Sheet 557). Calcium or vitamin D supplements may be helpful. This is especially true for people with osteopenia or osteoporosis.

Levels of lactic acid in the blood (lactic acidosis, see Fact Sheet 556) increase in some people taking tenofovir and emtricitabine. Liver problems including "fatty liver" may also occur.

In rare cases, people taking emtricitabine had some temporary changes in skin color.

Does PrEP Have Risks?

People with HIV have used Truvada, tenofovir and emtricitabine, for several years. They are generally easy to take. Possible long-term side effects include loss of bone mineral density and kidney damage.

Some people worry that people taking PrEP might think they are totally protected. They might be less careful about their sexual behavior. So far, this does not appear to be true.

The Bottom Line

Pre-exposure prophylaxis (PrEP) is the use of the antiretroviral medication Truvada before exposure to HIV, to reduce the risk of HIV infection. When Truvada as PrEP is used correctly and consistently, it can reduce the rate of HIV infection by sexual activity by as much as 90%.

The benefits of PrEP are potentially very high for reducing new HIV infections in people who recognize their risk of infection and can take Truvada to protect themselves. Some people fear PrEP may encourage unsafe behaviors, but this has not been seen.


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