Causes and triggers
HIV is spread through certain body fluids, including blood, semen, and vaginal secretions. A healthy person (who is not infected with the virus) can become infected from contact with the body fluids of an infected person. Transmission can occur through various types of contact, including the following:
- An injury from a needle potentially contaminated with HIV
- A cut
- A human bite
- Unprotected sex
Prophylaxis is used when a healthy person is exposed to one of these situations and there is a risk of HIV transmission.
Prophylaxis involves taking HIV medicines, called antiretroviral drugs. Antiretroviral medicines help prevent the spread of the virus in the body. Prophylaxis does not prevent infection in all cases. However, when used correctly, it is very effective.
To increase the chances of the treatment working, it is important to note the following:
- Treatment must be started no later than 72 hours after exposure (the earlier, the better)
- The drugs must be taken as prescribed (i.e., continuously and completely)
- Further exposure to HIV should be avoided during treatment by taking preventive measures (e.g., using a condom, not sharing needles)
In addition, to reduce the duration of contact with body fluids in the event of injury (needle sticks, cuts, scratches), it is recommended that the affected area be cleaned—but not scrubbed—with soap and water.
Post-exposure prophylaxis is an emergency measure and should not be used as a sole method of long-term HIV prevention. If you are at long-term risk, consult your health care provider to discuss your options.
When should I see a health care professional?
Consult a health care professional as soon as possible if you suspect you have been exposed to HIV. They will assess your risk of exposure in order to take the steps needed to ensure you have access to prophylaxis, if necessary.
CATIE (Canada's source for HIV and hepatitis C information)