This PE medicine is highly effective after 3 hours of dosage. Post-dosage, it can sometimes remain in your body for up to 12 hours. In general, the drug works in 8 out of 10 men. Over time, men using dapoxetine notice a doubling of the time their erection persists before ejaculation. Please note that this medicine is not a cure for PE. It will only work when you take it before sexual activity. Like some medicines, food may affect drug absorption.