# How long does sildenafil last? Updated October 17, 2026. Source: https://howlongdoessildenafillast.com/ ## Short answer About 4 hours. Sildenafil reaches its highest level in the blood about 1 hour after a dose, and in clinical testing its effect on erections lasted up to 4 hours, though it was weaker at 4 hours than at 2. It only works with sexual stimulation and does not cause an erection on its own.[1] ## Plan your timing | Want it working by | Take it (empty stomach) | Take it (after a heavy meal) | | --- | --- | --- | | 8:00 pm | 7:00 pm | 6:00 pm | | 9:00 pm | 8:00 pm | 7:00 pm | | 10:00 pm | 9:00 pm | 8:00 pm | Based on the FDA label: peak about 1 hour after a dose, about 1 hour later after a high-fat meal, and an effect lasting up to about 4 hours.[1] Follow your prescriber’s instructions first. ## Key facts - **Peak level:** About 1 hour after a dose on an empty stomach, within a 30 to 120 minute range.[1] - **Effect on erections:** Up to about 4 hours, stronger at 2 hours than at 4.[1] - **When to take it:** Usually 1 hour before sex. It can be taken anywhere from 30 minutes to 4 hours before.[1] - **Half-life:** About 4 hours for sildenafil and its active metabolite.[1] - **After a high-fat meal:** The peak comes about 1 hour later on average and is about 29% lower.[1] - **How often:** No more than once a day.[1] ## What happens after a dose | Time after dose | What happens | | --- | --- | | 30 to 120 minutes | Blood level peaks, typically around 1 hour on an empty stomach.[1] | | Around 2 hours | Effect on erections clearly present in the FDA label’s time-course study.[1] | | Around 4 hours | Effect still measurable, but weaker than at 2 hours.[1] | | After a heavy meal | Add about 1 hour to the times above.[1] | ## What changes how long it lasts - **Food:** A high-fat meal slows absorption, pushing the peak back by about an hour and lowering it.[1] - **Age 65 and over:** Older adults clear sildenafil more slowly. In healthy volunteers 65 and over, total exposure was about 84% higher than in younger adults, so a 25 mg starting dose may be considered.[1] - **Kidney or liver problems:** Severe kidney impairment and liver impairment raise blood levels. The label suggests considering a 25 mg starting dose.[1] - **Other medicines:** Drugs that block the CYP3A4 enzyme, such as ritonavir, ketoconazole, itraconazole and erythromycin, raise sildenafil levels. With ritonavir, the label limits sildenafil to a single 25 mg dose in 48 hours.[1] - **Dose:** In the label’s studies, response generally increased with dose. The usual dose is 50 mg, and a provider can adjust it between 25 and 100 mg.[1] ## When to get medical help - **An erection lasting more than 4 hours:** Get emergency care.[1] - **Sudden vision or hearing loss:** Stop taking sildenafil and get medical care right away.[1] - **Nitrates:** Never combine sildenafil with nitrates, such as nitroglycerin for chest pain. Together they can cause a serious drop in blood pressure.[1] ## Common questions ### Does sildenafil last 24 hours? No. Its effect on erections lasts up to about 4 hours.[1] If you want a longer window, tadalafil is a longer-acting medicine in the same class that a provider can discuss with you. ### Will I have an erection the whole time? No. Sildenafil helps an erection happen when you are sexually stimulated during that window. It does not cause a lasting erection on its own, and an erection over 4 hours is a medical emergency.[1] ### How long does it take to start working? Most people take it about an hour before sex, which matches the typical time to peak level. It can be taken as little as 30 minutes before.[1] ### Can I drink alcohol with sildenafil? In a study in the FDA label, a moderate amount of alcohol (blood alcohol around 0.08%) did not add to sildenafil’s effect on blood pressure in healthy volunteers.[1] ### Can I take a second dose if the first wears off? No. The maximum is one dose per day.[1] ## Next step **Find out if sildenafil is right for you.** Complete an online health assessment. A licensed provider reviews it and decides whether a prescription is appropriate. What the assessment includes: - Online health assessment - Review by a licensed provider - Shipped to you if prescribed - Card held at checkout, charged only if prescribed How to get started: 1. **Answer health questions.** An online assessment about your health, history and goals. 2. **A licensed provider reviews it.** They decide whether a prescription is safe and appropriate for you. 3. **If prescribed, it ships to you.** Your card is only held at checkout. You’re charged only if a provider prescribes. Not everyone qualifies. A provider decides based on your health history. Start the assessment: https://howlongdoessildenafillast.com/go/md/agent Assessments are completed with a partner telehealth provider. This site may earn a commission if you start one through it. ## Sources 1. VIAGRA (sildenafil citrate) tablets, full prescribing information. Pfizer, via U.S. Food and Drug Administration. Revised March 2014. https://www.accessdata.fda.gov/drugsatfda_docs/label/2014/20895s039s042lbl.pdf --- General education, not medical advice. Talk to a licensed clinician before starting or changing any medicine.