Yes, PEP must be taken within 72 hours (3 days) of possible HIV exposure for it to work. This is the global medical guideline, including in Singapore. However, the sooner you start—preferably in the first 24 hours—the higher the success rate.
If you start PEP after 72 hours, its effectiveness drops significantly, and most doctors will not prescribe it because it may not provide meaningful protection anymore.
If you think you’ve had a high-risk exposure, visit a hospital emergency department or a sexual health clinic in Singapore immediately, rather than waiting. Acting fast is crucial for PEP to be effective.