How does PrEP work?
PrEP contains antiretroviral medicines that stop HIV from multiplying in the body. If HIV enters the bloodstream, PrEP prevents it from taking hold and spreading, significantly lowering the risk of infection.
What is PrEP used for?
PrEP is prescribed to reduce the risk of HIV in people who:
- Have a partner living with HIV who is not on effective treatment
- May be exposed to HIV through unprotected sex
- Have been advised by a healthcare professional that they may benefit from HIV prevention
Who can take PrEP?
Most adults and young people at risk of HIV exposure can take PrEP. It is prescribed after a discussion with a doctor, nurse, or sexual health specialist to assess individual risk factors.
Who might not be able to take PrEP?
PrEP may not be suitable if you:
- Have HIV (PrEP is only for HIV-negative individuals)
- Have kidney or liver disease (as PrEP can affect kidney function)
- Cannot take it consistently, as irregular use reduces its effectiveness
Can I take PrEP if I’m pregnant or breastfeeding?
PrEP can be taken during pregnancy and breastfeeding if there is a higher risk of HIV exposure. A doctor can provide guidance on whether PrEP is the right option for you.
What if I miss a dose?
- Daily PrEP: Take the missed dose as soon as you remember, but do not double up.
- On-demand PrEP: If you miss a dose before sex, the effectiveness may be reduced. Speak to a healthcare professional for advice.
How effective is PrEP?
PrEP is over 99% effective in preventing HIV when taken as prescribed:
- Daily use: Provides continuous protection
- On-demand use: Highly effective when taken correctly (but consult a doctor for advice on suitability)
What should I do if I take too much?
PrEP is generally safe, but if you take more than prescribed and feel unwell, contact a healthcare professional.
What dose of PrEP is usually taken?
- Daily PrEP: One tablet per day
- On-demand PrEP: Two tablets before sex, followed by one tablet 24 hours later and another 48 hours after the first dose
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What are the side effects of PrEP?
Most people tolerate PrEP well, but some may experience:
- Nausea
- Headache
- Mild stomach discomfort
- Temporary changes in kidney function (monitored through blood tests)
Serious side effects are rare.
How should I take PrEP?
PrEP is taken as a tablet, with or without food. Regular HIV and kidney function tests are recommended while taking PrEP.
When should PrEP be taken?
- Daily PrEP: Taken at the same time each day
- On-demand PrEP: Taken before and after potential exposure
What are the brand names for PrEP?
PrEP is available under brand names such as Truvada and generic versions containing tenofovir disoproxil and emtricitabine.
Final thoughts
PrEP is a highly effective tool in HIV prevention when taken correctly. It is available through the NHS in the UK for those who may be at higher risk. If you think PrEP might be right for you, speak to a healthcare professional for personalised advice.
