Yes, food can slow Viagra down, but it does not stop it working. Taken with food, sildenafil is absorbed more slowly: on average its peak level in the blood arrives about 60 minutes later and is 29% lower than when it is taken on an empty stomach (EMA product information). The Australian leaflet puts it in plain words: it may take longer to work if you take it with a heavy meal (Viagra CMI).
How does food change the way sildenafil is absorbed?
It changes the speed. On an empty stomach, sildenafil reaches its highest level in the blood within 30 to 120 minutes, 60 minutes in the middle case; with food, the rate of absorption drops. These are the label's figures for Viagra absorption with and without food:
| Empty stomach | With food | |
|---|---|---|
| Time to the highest blood level | 30 to 120 minutes (median 60) | About 60 minutes later, on average |
| Highest blood level | The reference | 29% lower, on average |
| What the leaflet says | Take it about one hour before sex | May take longer to work after a heavy meal |
Sources: EMA product information, section 5.2; Viagra CMI. Generic sildenafil tablets contain the same medicine, so the same food effect applies to them.
How long before sex should you take it?
About one hour before you intend to have sex (Viagra CMI). It usually starts working in 30 to 60 minutes, and its effects can last for up to 4 hours (healthdirect). Because a meal can delay the onset of action by around an hour on average, allow more time if you have just eaten a large meal. It will not work without sexual stimulation, whatever you ate (EMA).
Do you have to take it on an empty stomach?
No. You do not have to take Viagra on an empty stomach: the label's only warning about food is that it may delay the start compared with taking it fasted (EMA). If timing matters to you, take the tablet before a big meal rather than straight after one.
Which foods slow it down the most?
Neither the Australian leaflet nor the European label names particular foods. The leaflet warns about a heavy meal, and the label measured the effect of food in general. Lists of "fatty foods to avoid" go further than the evidence on the label does.
Does grapefruit juice affect Viagra?
A little. Grapefruit juice weakly blocks one of the enzymes in the gut wall that break sildenafil down, and may give rise to modest increases in its level in the blood (EMA product information). The label gives no percentage for grapefruit. Stronger blockers of the same enzyme, such as the antifungal ketoconazole or the antibiotic erythromycin, matter far more: with them, a 25mg starting dose should be considered.
Can you drink alcohol with it?
Go carefully. The leaflet says to be careful drinking alcohol while taking Viagra, because alcohol can temporarily impair the ability to get an erection (Viagra CMI). In a volunteer study, sildenafil 50mg did not add to the drop in blood pressure caused by alcohol at a mean peak blood alcohol level of 80 mg/dL (EMA product information), so the practical problem with drinking is the erection, not the tablet.
Which medicines matter more than food?
Nitrates, the medicines for angina, and guanylate-cyclase stimulators such as riociguat: never take sildenafil with them (EMA). healthdirect also lists amyl nitrite and blood pressure medicines, which can cause a sudden drop in blood pressure that is hard to treat (healthdirect). Men on an alpha-blocker for blood pressure or the prostate should be stable on it before starting, and the label suggests a 25mg first dose (EMA product information). Sildenafil is prescription-only in Australia (healthdirect); if you take an alpha-blocker or another blood pressure medicine, consult your healthcare provider to discuss the optimal way to administer Viagra based on your individual circumstances.
What is the simplest way to time it around a meal?
- Take it about an hour before sex, and earlier if you have just had a heavy meal.
- Expect it to work for up to about 4 hours, and only with sexual stimulation.
- Keep grapefruit juice and alcohol modest.
- Take no more than one tablet in 24 hours (healthdirect).
