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, counseling, and regular monitoring. WHO: Pre-exposure prophylaxis.
It is important to differentiate clearly: PrEP protects against HIV but not against other sexually transmitted infections. For those, testing, condoms, and vaccinations where applicable remain relevant.
How well PrEP protects
When taken correctly, PrEP is highly 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 regularly. CDC: PrEP effectiveness.
The percentage alone is not the only important point; it is the underlying logic. PrEP works reliably when sufficient drug levels are present in the body at the critical time. Irregular use is the most common reason for reduced protection.
Who may benefit from PrEP
PrEP is aimed at situations with increased HIV risk, not at specific identities. It can be appropriate when other prevention strategies are insufficient or cannot be used reliably.
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 circumstances and available protections
- partnerships with an HIV-positive person without confirmed sustained viral suppression
- situations where injection equipment may be shared
Whether PrEP fits into your life is best determined in a brief, structured counseling session.
Forms of PrEP dosing
Daily oral PrEP is the international standard. Event-driven regimens also exist but are not equally studied for all groups and are not recommended everywhere.
Daily PrEP
With daily PrEP, one pill is taken each day. The advantage is a stable drug level and a simple routine. For many people, this is the most reliable option because it does not depend on individual situations.
Event-driven PrEP
Event-driven PrEP is taken around expected sexual encounters. It requires precise timing and is not suitable for everyone or every situation. Clinical counseling is particularly important here.
When PrEP becomes effective
How quickly PrEP protects depends on the dosing regimen, tissue, and type of exposure. Guidelines therefore give deliberately conservative recommendations and emphasize individualized counseling at initiation.
In the start-up phase it is sensible to take PrEP consistently and not to shortcut the process, even if the perceived risk seems low.
Which tests and monitoring are required
PrEP is always linked to medical supervision. Before starting, an HIV infection must be reliably excluded, and regular monitoring is necessary during use. HIV testing is often recommended about every three months, supplemented by other examinations based on the risk profile. RKI (Germany): FAQ on HIV PrEP.
Typically included are:
- HIV test before starting and at regular intervals
- tests for other sexually transmitted infections
- monitoring of kidney function
- counseling about dosing, side effects, and drug interactions
This structure serves safety. It is especially important to reliably exclude HIV before starting, because PrEP is not suitable to treat 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. Long-term concerns mainly involve kidney values and, in some situations, bone density, which is why regular monitoring is part of care.
A current clinical reference is the German-Austrian S2k guideline on HIV pre-exposure prophylaxis. AWMF: S2k guideline on HIV PrEP.
Drug interactions and concomitant medication
Interactions are overall uncommon but possible. Of particular relevance are medications or conditions that can affect kidney function. Open communication about all regularly taken medicines is part of safe use.
PrEP in partnerships
In steady partnerships, PrEP can provide temporary additional protection—for example, when a partner's HIV status is unclear or viral suppression has not yet been confirmed. A joint plan is more helpful than unspoken assumptions.
If an HIV-positive partner has a sustained undetectable viral load, the sexual transmission risk is generally extremely low. Nevertheless, PrEP can be subjectively relieving during transition phases or when uncertainty remains.
PrEP, pregnancy, and trying to conceive
PrEP can play a role in certain situations around pregnancy or conception, such as in serodiscordant partnerships. In these cases individualized counseling is particularly important to align benefits and monitoring.
Using PrEP effectively in everyday life
PrEP works best when it is understood as part of a clear plan. This includes regular dosing, testing, and a realistic approach to risks.
- Treat PrEP as a routine
- attend follow-up appointments reliably
- seek medical advice early if you have symptoms or uncertainty
- consider STI testing a normal part of sexual health
Costs and practical planning
Access and costs vary widely between countries. In some places PrEP is part of public health coverage; in others it must be paid privately or is tied to specific programs.
If you travel or will be abroad for an extended period, check in advance how tests, prescriptions, and medication supply can be organized.
Legal and regulatory context
Prescription requirements, monitoring obligations, coverage of costs, and available formulations differ by country. These rules can change and should be checked for current accuracy.
For international readers: PrEP should always be used according to 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: Situational risk, not identity, determines suitability.
- Myth: People on PrEP do not need tests. Fact: Regular testing is a central part of safe use.
- Myth: PrEP inevitably damages the kidneys. Fact: Most people tolerate PrEP well; monitoring is preventive.
- Myth: Irregular dosing is sufficient. Fact: Protection depends strongly on consistent dosing.
- Myth: PrEP and PEP are identical. Fact: PrEP is preventive; PEP is used after possible exposure.
When medical advice is especially important
Even while taking PrEP, there are situations where renewed counseling is advisable or necessary.
- Symptoms that could indicate acute HIV infection
- long interruptions in dosing
- new medications or illnesses that may affect kidney function
- pregnancy, breastfeeding, or a specific desire to conceive
- recurrent STI diagnoses requiring adjustment of the 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 can significantly increase safety as part of a clear prevention plan. Key elements 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.
