What PrEP is and what it is not
PrEP stands for pre-exposure prophylaxis. It refers to the preventive use of certain HIV medications by HIV-negative people to prevent HIV infection. PrEP is not a substitute for medical care, but part of a structured prevention approach that includes testing, counselling and regular monitoring. WHO: Pre-exposure prophylaxis.
It is important to be clear: PrEP protects against HIV, but not against other sexually transmitted infections. For these, testing, condoms and, where appropriate, vaccinations remain relevant.
How well PrEP protects
With correct use, PrEP is very effective. Large studies and public health data show that the risk of HIV from sexual contact can be reduced by about 99 percent when PrEP is taken consistently. CDC: PrEP effectiveness.
The percentage alone is not the only point; the underlying logic matters. PrEP works reliably when enough drug is present in the body during the relevant time period. Irregular dosing is the most common reason for reduced protection.
Who may benefit from PrEP
PrEP is aimed at situations with increased HIV risk, not at particular identities. It can be appropriate when other prevention strategies are insufficient or cannot be relied on.
Typical situations include:
- sex with partners whose HIV status is unknown or who do not have documented sustained viral suppression
- frequent changing sexual partners, especially without consistent condom use
- sex work, depending on context and available protections
- partnerships with an HIV-positive person without confirmed sustained viral suppression
- situations where injection equipment might be shared
Whether PrEP fits into your routine is best determined in a short, structured consultation.
Forms of PrEP dosing
Daily oral PrEP is the international standard. There are also event-based regimens, but these have not been equally studied for all groups and are not recommended everywhere.
Daily PrEP
Daily PrEP involves taking one pill per day. The advantage is a steady drug level and a simple routine. For many people this is the most reliable option because it is independent of specific situations.
Event-based PrEP
Event-based PrEP is taken around anticipated sexual encounters. It requires precise timing and is not suitable for everyone or every situation. Medical counselling is particularly important here.
When PrEP starts to work
How quickly PrEP provides protection depends on the dosing regimen, tissue and type of exposure. Guidelines therefore tend to give conservative recommendations and emphasise individual counselling at the start.
In the initiation phase it is sensible to take PrEP consistently and not to cut corners, even if the perceived risk seems low.
What tests and monitoring are required
PrEP should always be provided with medical supervision. Before starting, HIV infection must be reliably excluded, and regular monitoring is necessary during use. HIV tests are often recommended about every three months, supplemented by other examinations depending on the risk profile. RKI: FAQ on HIV PrEP.
Typical components include:
- HIV testing before starting and at regular intervals
- testing for other sexually transmitted infections
- kidney function monitoring
- counselling on dosing, side effects and interactions
This structure exists for safety. It is especially important to reliably exclude HIV before starting, since PrEP is not suitable for treating an existing infection.
Side effects and tolerability
Most people tolerate PrEP well. In the first days or weeks mild symptoms such as nausea, headache or fatigue may occur and usually resolve. In the long term, kidney values and, in certain situations, bone density are most relevant, which is why regular monitoring is included.
A recent clinical orientation is provided by the S2k guideline on HIV pre-exposure prophylaxis. AWMF: S2k guideline on HIV pre-exposure prophylaxis.
Drug interactions and concomitant medication
Interactions are overall uncommon but possible. Relevant are mainly medications or conditions that can affect the kidneys. Open communication about all regularly taken medications is part of safe use.
PrEP in partnerships
In steady partnerships, PrEP can provide additional protection for a period, for example when the HIV status is unclear or viral suppression has not yet been confirmed. A shared plan is more helpful than assumptions.
If the viral load of an HIV-positive partner is consistently below the limit of detection, the sexual transmission risk is typically extremely low. Nevertheless, PrEP can be reassuring during transition phases or when there is uncertainty.
PrEP, pregnancy and planning for children
PrEP can play a role in certain situations around conception or pregnancy, for example in serodifferent partnerships. In these cases individual counselling is particularly important to appropriately weigh benefits and monitoring.
Using PrEP sensibly in everyday life
PrEP works best when it is part of a clear plan. This includes regular dosing, testing and a realistic approach to risks.
- treat PrEP as a fixed routine
- attend follow-up appointments reliably
- seek medical advice early if you have symptoms or uncertainties
- consider STI testing a normal part of sexual health
Costs and practical planning
Access and costs vary considerably between countries. In some places PrEP is part of public health coverage, in others it must be paid for privately or is tied to specific programmes.
If you travel or will be abroad for an extended period, you should clarify in advance how tests, prescriptions and medication supply can be organised.
Legal and regulatory context
Prescription requirements, monitoring obligations, cost coverage and available products differ by country. These rules can change and should be checked for currency.
For international readers: PrEP should always be used within the framework of local medical and legal requirements.
Myths and facts about PrEP
- Myth: PrEP protects against all sexually transmitted infections. Fact: PrEP protects against HIV, not other STIs.
- Myth: PrEP is only for certain groups. Fact: What matters are risk situations, not identities.
- Myth: People on PrEP do not need tests. Fact: Regular testing is a central component of safety.
- Myth: PrEP inevitably damages the kidneys. Fact: Most people tolerate PrEP well; monitoring is preventive.
- Myth: Irregular dosing is sufficient. Fact: Protection depends heavily on reliable dosing.
- Myth: PrEP and PEP are the same. Fact: PrEP is preventive; PEP is given after possible exposure.
When medical advice is particularly important
Even while taking PrEP, there are situations where renewed medical advice is advisable or necessary.
- symptoms that could indicate acute HIV infection
- prolonged interruptions in dosing
- new medications or conditions that may affect the kidneys
- pregnancy, breastfeeding or planning for children
- repeated STI diagnoses requiring adjustment of prevention strategy
Conclusion
PrEP is a highly effective and well-studied method of HIV prevention when used correctly. It does not replace testing or medical supervision, but as part of a clear prevention plan it can significantly increase safety. Key factors are realistic expectations, reliable dosing and regular monitoring.
A neutral government overview with basic current information is available from HIV.gov. HIV.gov: Pre-exposure prophylaxis.
