PrEP Side Effects — What to Actually Expect

If you're considering PrEP and worried about side effects, here's the honest picture. Most people tolerate PrEP very well. The vast majority of side effects are mild and clear up in the first few weeks. Serious side effects exist but are uncommon.

This guide covers the three current PrEP regimens (Truvada, Descovy, Apretude/cabotegravir injection) and what's actually known about each.

The short answer

Most-cited side effects across all PrEP regimens:

• Start-up GI upset (~10-15% of users; clears in 1-4 weeks)
• Mild headache (~5-10%; transient)
• Fatigue or sleep changes (~5%; usually mild)
• Mild kidney function changes (monitored; rarely clinically significant)
• Modest bone density changes with Truvada (long-term; clinically meaningful only in specific populations)

These are the things you might actually notice or have monitored. Most users on PrEP for a year have no clinically significant issues.

Daily oral PrEP — Truvada and Descovy

Truvada (tenofovir disoproxil fumarate + emtricitabine)

The original PrEP. Generic available; cheap.

Common side effects (first 1-4 weeks):

• Nausea (10-15%)
• Diarrhea or stomach upset (5-10%)
• Headache (5-10%)
• Fatigue
• Sometimes dizziness

These typically resolve within a few weeks as your body adjusts. Taking with food helps with GI side effects. Most people who quit PrEP cite the first-month "start-up" period.

Long-term considerations:

• Mild kidney function decline in a small percentage; monitored every 3-6 months
• Slight bone mineral density reduction (~1-2%); typically not clinically significant
• These effects reverse when PrEP is stopped

Who should NOT use Truvada:

• Kidney function below eGFR 60 mL/min
• People with bone-density concerns (osteoporosis, recent fractures) — Descovy is often preferred

Descovy (tenofovir alafenamide + emtricitabine)

Newer formulation. More expensive but easier on kidneys and bones.

Common side effects:

• Similar GI start-up to Truvada (~10-15%)
• Possibly slightly less nausea and fatigue in reported trials
• Modest weight gain in some users (~1-2 kg average over first year)
• Modest lipid/cholesterol changes (worth monitoring)

Long-term considerations:

• Better kidney and bone profile than Truvada
• The weight and cholesterol changes are the main long-term differentiators

FDA-approved for:

• All HIV prevention scenarios EXCEPT receptive vaginal sex (data still being gathered for that population)

Choosing between Truvada and Descovy

• Insurance and cost often decide — Truvada generic is much cheaper
• Pre-existing kidney or bone concerns favor Descovy
• Weight or lipid concerns may favor Truvada
• Both work — the choice is about your specific profile

Long-acting injectable PrEP — Apretude (cabotegravir)

Approved 2021. Every 2 months injection (after a 1-month lead-in).

Common side effects:

• Injection site reaction (the big one) — soreness, swelling, redness at the buttock injection site for 1-7 days
  • Reported by ~80% of users in clinical trials
  • Usually mild; rarely interferes with daily activities
• Headache (~5-10%)
• Nausea (~5-10%)
• Fatigue (~5%)
• Fever or flu-like symptoms in the first 24-48 hours (uncommon)

Long-term considerations:

• Lower viral load testing accuracy if you become HIV-positive on it (less of a concern given the prevention efficacy)
• No kidney or bone concerns like oral options
• Discontinuation requires careful planning — virus levels in the body take weeks to wash out, so you transition to oral PrEP first

When Apretude is the better choice

• Adherence is the main concern for oral PrEP
• Travel-heavy lifestyle (no daily pill needed)
• Pre-existing kidney concerns ruling out Truvada
• Personal preference for not thinking about it daily

When Apretude is NOT the right choice

• You're avoiding injections (some people)
• You're starting PrEP urgently (the lead-in period means it's not immediate)
• Insurance doesn't cover it (Apretude is more expensive than oral PrEP)

Twice-yearly injectable — Lenacapavir (PURPOSE)

FDA-approved for PrEP in 2024 after the PURPOSE-1 and PURPOSE-2 trials. Subcutaneous injection every 6 months.

Common side effects:

• Injection-site reactions (the major issue) — local nodule, redness, soreness lasting up to 2 weeks
• Headache (~10%)
• Nausea (~5%)
• Body temperature changes (uncommon)

Long-term considerations:

• Long-term data is still accumulating
• The 6-month dosing creates fewer adherence touchpoints — best-in-class for people who struggle with even injectable cabotegravir's bi-monthly schedule
• Discontinuation timing matters; transition to oral PrEP before stopping

When Lenacapavir is the right choice

• Maximum convenience needed
• Bi-monthly Apretude is still too frequent
• Studies showed near-100% efficacy in women in sub-Saharan Africa

Note: rollout is still ongoing in the US as of mid-2026. Availability varies by clinic.

Side effects that warrant a call to your provider

For any PrEP regimen, contact your provider if:

• Persistent GI upset more than 4-6 weeks
• Persistent kidney symptoms (decreased urination, swelling in legs)
• New bone pain or fracture
• Yellowing of skin or eyes (rare hepatitis signal)
• Severe injection site reaction (cellulitis-like)
• New, persistent rash
• Mood changes or depression (rare but documented with some HIV medications)
• Pregnancy (PrEP is generally safe in pregnancy but worth discussing)

What's NOT a typical PrEP side effect

• Weight loss
• Severe fatigue lasting months
• Loss of appetite
• Tinnitus
• Joint pain
• Vision changes
• Cognitive changes (sometimes attributed to PrEP but rarely from it)

If you're experiencing these on PrEP, look for other causes first. PrEP is not generally implicated.

Monitoring schedule on PrEP

Every 3 months (oral PrEP):

• HIV test (must remain negative)
• Kidney function (creatinine, eGFR)
• Pregnancy test if applicable
• STI screening (gonorrhea, chlamydia, syphilis)
• Discuss any side effects

Every 6-12 months:

• Hepatitis B status
• More comprehensive STI panel
• Liver function (if specific concerns)

For injectable PrEP, schedule depends on the injection cadence. Apretude users get HIV testing before each injection (every 2 months).

Side effect comparison summary

What if you can't tolerate one PrEP?

Switching is straightforward:

• Talk to your provider
• For oral-to-oral switch: just start the new one
• For oral-to-injectable: stop oral and start injectable on the same day
• For injectable-to-oral: more careful timing because of the long washout

If PrEP doesn't work for you at all, condoms + suppressive HIV-positive partner treatment + careful partner choice still provide significant protection.

A note on placebo and nocebo

Side effects in PrEP trials show a meaningful placebo effect. Some "PrEP side effects" reported by users are actually from other causes — diet, sleep, stress, other medications, normal life. Track symptoms for a week before assuming PrEP is the cause.

That said: if you genuinely feel worse on PrEP and can't pin down another cause, your experience is real. Talk to your provider about switching.

Bottom line

PrEP is well-tolerated by the vast majority of users. The first month is the hardest, and most people are fine after that. The benefits — near-elimination of HIV acquisition risk — outweigh the side effects for almost everyone in the eligible population.

If you're hesitating because of side effect concerns, it's worth talking to a provider about which regimen is best for your specific situation rather than ruling it out entirely.

For more on HIV prevention overall: PrEP vs PEP guide. For broader HIV info: HIV pillar guide.