What PrEP is and what it is not
PrEP stands for pre-exposure prophylaxis. It means 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 those, testing, condoms and, where appropriate, vaccination 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 consistently. CDC: PrEP effectiveness.
The percentage alone is not the whole story; what matters is the underlying logic. PrEP works reliably when sufficient drug levels are present in the body during the relevant time. Irregular use is the most common reason for reduced protection.
Who may benefit from PrEP
PrEP is aimed at situations with increased risk of HIV, not at particular identities. It may be useful when other prevention strategies alone are insufficient or cannot be implemented reliably.
Typical situations include:
- sex with partners whose HIV status is unknown or whose sustained viral suppression is not known
- frequent changing sexual partners, especially without consistent condom use
- sex work, depending on context and available protection measures
- partnerships with an HIV-positive person without proven long-term viral suppression
- situations where injecting equipment may be shared
Whether PrEP fits into one’s life is best determined during a short, structured counselling session.
Forms of PrEP administration
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 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-based PrEP
Event-based PrEP is taken around expected sexual exposures. It requires precise timing and is not suitable for everyone or every situation. Medical counselling is particularly important for this approach.
When PrEP starts to protect
How quickly PrEP provides protection depends on the regimen, the tissue involved and the type of exposure. For this reason, guidelines tend to give conservative recommendations and emphasise individual counselling at the start.
During the initiation phase it is sensible to take PrEP consistently and avoid shortcuts, even if the perceived risk seems low.
Which tests and monitoring are required
PrEP is always 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 tests depending on the risk profile. ICMR/NACO: FAQ on HIV PrEP.
Typically this includes:
- HIV test before starting and at regular intervals
- tests for other sexually transmitted infections
- monitoring of kidney function
- counselling on use, side effects and drug interactions
This structure is for 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 tiredness can occur and usually subside. Longer-term concerns mainly relate to kidney function and, in certain cases, bone density, which is why regular monitoring is necessary.
A current clinical reference is provided by the national guideline on HIV pre-exposure prophylaxis. ICMR: National guideline on HIV PrEP.
Drug interactions and concurrent medications
Interactions are generally rare but possible. Of particular relevance are drugs or conditions that affect the kidneys. Open communication about all regularly taken medicines is part of safe use.
PrEP in partnerships
In stable partnerships, PrEP can sometimes provide additional protection, for example when a partner’s HIV status is unclear or viral suppression is not yet proven. A shared plan is more helpful than unspoken assumptions.
If the viral load of an HIV-positive partner is durably below the limit of detection, the sexual transmission risk is generally extremely low. Nevertheless, PrEP can be reassuring during transition phases or where uncertainty remains.
PrEP, pregnancy and planning a pregnancy
PrEP can play a role in certain situations around pregnancy and planning for children, for example in serodifferent partnerships. In these cases individual counselling is particularly important to balance benefits and monitoring.
Using PrEP sensibly in everyday life
PrEP works best when it is part of a clear plan. This includes regular dosing, tests and a realistic approach to risks.
- Treat PrEP as a regular routine
- attend monitoring appointments reliably
- seek medical advice early for symptoms or uncertainty
- consider STI testing as 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 services, while in others it is privately funded or linked to specific programmes.
If you travel or stay abroad for an extended period, check in advance how tests, prescriptions and supply will be organised.
Legal and regulatory context
Prescription requirements, monitoring obligations, cost coverage and available formulations differ by country. These rules can change and should be checked for the current local situation.
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: It is the risk situation that matters, not identity.
- 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 reliable dosing.
- Myth: PrEP and PEP are identical. Fact: PrEP is preventive; PEP is used after a possible exposure.
When medical advice is particularly important
Even while taking PrEP, there are situations where renewed medical advice is sensible or necessary.
- symptoms that could suggest an acute HIV infection
- long interruptions in taking PrEP
- new medications or illnesses that may affect kidney function
- pregnancy, breastfeeding or specific plans for pregnancy
- recurrent 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 can significantly increase safety as part of a clear prevention plan. Realistic expectations, reliable dosing and regular monitoring are crucial.
A neutral government overview is available from NACO with basic information. NACO: Pre-exposure prophylaxis.
