HIV pre-exposure prophylaxis (PrEP) in Singapore.

HIV PrEP (pre-exposure prophylaxis) is a prescription medication taken by HIV-negative individuals to prevent HIV infection. It is an established preventive intervention when taken as prescribed.⁵

What PrEP is. PrEP is typically a daily or on-demand tablet containing TDF/FTC or TAF/FTC. In Singapore, these are dispensed as originator tablets, not generics. The same medications are also part of HIV treatment regimens; used preventively in HIV-negative individuals, they prevent the virus from establishing infection if exposure occurs.

How effective PrEP is. When taken as prescribed (daily or correctly on-demand), PrEP substantially reduces sexual HIV transmission. Effectiveness drops with missed doses - adherence is the single biggest factor in real-world outcomes. PrEP also reduces transmission via injection drug use, though by a somewhat smaller margin.

Who PrEP is for. PrEP is appropriate for any HIV-negative person with ongoing potential exposure to HIV through sexual contact. The clinical guidelines are not restrictive - anyone who wants additional protection and meets basic safety criteria can consider PrEP. Common situations include: partner of a person living with HIV (particularly during conception planning or if their viral load is not yet undetectable); sexual contact with multiple partners or higher-frequency activity; inconsistent condom use; history of multiple STIs; recent PEP use suggesting ongoing exposure risk.

Who PrEP is not for. People already living with HIV (full HIV treatment regimens are needed instead); anyone with significantly reduced kidney function; anyone with chronic hepatitis B taking certain other treatments; anyone with allergy to the components. A baseline workup determines eligibility individually. Most people are eligible.

Singapore context. PrEP is available in Singapore through private clinics like Hisential. It is not currently subsidised under the public healthcare system - it is a private, paid preventive intervention requiring prescription after a baseline HIV-negative test. Quarterly clinical and laboratory monitoring is required for ongoing prescription.

PrEP is most effective when used as part of a comprehensive sexual health strategy - alongside condoms (which prevent other STIs), routine STD testing, vaccinations, and informed sexual decisions. It is not a replacement for condoms but a powerful addition.

The medications. The daily PrEP regimen is a combination tablet containing TDF/FTC or TAF/FTC. Both work by blocking reverse transcriptase, an enzyme HIV uses to integrate into host cells. When the drugs are present in tissue at adequate concentration, HIV cannot establish infection even if exposure occurs.

Two dosing regimens.

Daily PrEP - one tablet of TDF/FTC or TAF/FTC every day at approximately the same time. The most studied regimen with the most flexible application - protection extends across all sexual contact, including unplanned situations. After 7 days of daily dosing, full protection is established for rectal exposure; 21 days for vaginal exposure.⁵

On-demand (2-1-1) PrEP - event-driven dosing for individuals whose situations are predictable enough to plan around: 2 tablets of TDF/FTC taken 2-24 hours before sex (ideally 2-12 hours), 1 tablet 24 hours after the first 2-pill dose, and 1 tablet 48 hours after the first 2-pill dose. If multiple sexual encounters occur over several days, continue with 1 tablet daily during the active period, then continue 2 days after the last encounter. On-demand dosing is well-studied for men who have sex with men (MSM); it is less established for women due to slower drug accumulation in vaginal tissue. On-demand dosing has not been studied with TAF/FTC.⁴

Effectiveness by adherence. Daily PrEP with near-perfect adherence is the most protective option.⁵ Daily PrEP with occasional missed doses (4+ tablets per week) is somewhat less protective. With frequent missed doses (under 2 tablets per week), effectiveness drops substantially. On-demand 2-1-1 taken correctly is comparable to daily PrEP for MSM.⁴ Adherence is the single biggest factor.

Side effects. Generally well-tolerated. Most common in the first month: mild gastrointestinal upset, headache, fatigue - usually resolving. Rare but more serious: kidney function changes (monitored quarterly with creatinine and eGFR), small bone mineral density changes (usually clinically insignificant), hepatitis B flare on stopping if hepatitis B carrier (managed through coordinated care). For most users, PrEP is taken indefinitely with no significant ongoing effects.

What PrEP does not protect against. PrEP prevents HIV. It does not prevent other STIs - chlamydia, gonorrhoea, syphilis, hepatitis, HPV, herpes. This is why structured STD testing at least every 3 months is part of PrEP care. Condoms remain valuable for combined HIV and STI prevention.

Comprehensive care integration. PrEP at Hisential is integrated with STD testing, HIV testing, vaccination (hepatitis B, HPV), and STD treatment if any concurrent infection is detected. HIV PEP is available for any specific high-risk exposure that occurs while not on PrEP or with significant PrEP non-adherence.

Before your visit. Your personal health concierge shares a brief intake form covering general health, current medications, and any specific questions or concerns. Bring identification for laboratory testing.

During your visit. The initial PrEP consultation lasts 45-60 minutes - longer than routine visits because we are planning a long-term intervention. Our medical team takes a focused history covering reasons for considering PrEP, sexual activity context, current prevention strategies, prior STI history, current medications, kidney health, hepatitis B status if known, and any specific questions.

The conversation is matter-of-fact and respect-based - your reasons for considering PrEP do not require justification. The clinical task is matching the right regimen to your situation and making sure baseline workup is safe.

Examination is brief and usually limited. Sample collection: blood draw for HIV, kidney function, hepatitis B and C, syphilis, and other tests as relevant. Urine sample for chlamydia and gonorrhoea. Pharyngeal and/or rectal swabs if appropriate. If you would like a rapid HIV test result during the consultation, that is available - useful for those who want immediate confirmation of HIV-negative status before starting.

Prescription is typically not given at the first visit - we wait for full baseline results (typically 3-5 working days) before initiating PrEP. This ensures safety. In some situations, an immediate empirical start is appropriate; this is discussed individually.

After your visit. Your personal health concierge contacts you with baseline results. If all clear and PrEP is appropriate, prescription is issued. First refill is typically for 1 month while we confirm tolerability; subsequent refills are 3-monthly aligned with the quarterly visit. Quarterly visits follow - 15-20 minutes each, with blood draw and brief review.

Confidentiality. Records are encrypted. Hisential does not share information with employers, family members, or insurers without your explicit consent, except where required by regulations or law. PrEP prescriptions are not added to any external medical record without your specific approval, except where required by regulations or law.