Can you take Viagra twice in one day? No: one dose in 24 hours is the limit. "You should not take any more than one sildenafil tablet in 24 hours" (healthdirect), and the Australian leaflet says "Do not take more than one dose of VIAGRA a day" (Viagra CMI). Two days in a row is a different question: the limit is one tablet in any 24 hours, so a tablet on each of two days, a full day apart, stays within it. What the label does not offer is a daily sildenafil routine for erectile dysfunction.
Why not a second tablet on the same day?
Because a second tablet adds side effects, not a better erection. The package leaflet says that if you take more than you should, "You may experience an increase in side effects and their severity. Doses above 100 mg do not increase the efficacy" (EMA package leaflet). The usual dose is 50 mg, adjusted to 25 mg or to a maximum of 100 mg by effect and side effects (EMA), and "one 25 mg tablet, one 50 mg tablet, or one 100 mg tablet per day" is the whole range (Viagra CMI). A second 50 mg tablet on top of a first is not a way to reach 100 mg; how the two strengths differ is in what is the difference between 50 mg and 100 mg Viagra?
Nor is there a gap to fill: sildenafil usually starts working in 30 to 60 minutes and its effects can last for up to 4 hours (healthdirect).
Can you take Viagra two days in a row?
Yes, if the doses are at least 24 hours apart. The label limits how often you take it, "once per day" (EMA product information), not how many days in a row. A tablet late on Saturday and another early on Sunday would break the 24-hour rule even though they fall on different days. Sildenafil clears fairly quickly, with a half-life of 3 to 5 hours (EMA product information): every 3 to 5 hours the amount in your blood halves. More on that in the half-life of Viagra.
What the label does not give is a daily sildenafil dose for erections: it is taken as needed, about an hour before sex (EMA). If you expect to need a tablet twice a week or more, the ED medicine that has a daily dose is tadalafil, 5 mg once a day (EMA); its rules are in can I take several doses of Cialis in a day or on consecutive days? and the sildenafil side of the question in is it OK to take Viagra every day?
What if the first tablet did not work?
Do not take another; tell your doctor. The leaflet says: "If VIAGRA does not help you get an erection or if your erection does not last long enough to complete sexual intercourse, tell your doctor. In these cases, your doctor may decide that you need a higher dose" (Viagra CMI). Check the basics first. Viagra "will work only if you are sexually excited"; take it about one hour before sex; and "You may find VIAGRA takes longer to work if you take it with a heavy meal" (Viagra CMI). How food changes the timing is in the effect of food on Viagra absorption; what a first dose is like, in what to expect when taking Viagra for the first time; and the other reasons it can fail, in why Viagra may not work.
Why do some people take sildenafil three times a day?
Because that is a different medicine for a different disease. Revatio contains sildenafil and treats pulmonary arterial hypertension, high blood pressure in the arteries of the lungs; "In adults, Revatio is taken at a dose of 20 mg three times a day", and it is started and monitored by a doctor with experience in that disease (EMA). That schedule says nothing about Viagra for erections, where one dose a day remains the limit. More in sildenafil for pulmonary hypertension.
What should you do if you have taken two doses?
Get advice now rather than waiting to see. The Australian leaflet says to phone the Poisons Information Centre on 13 11 26, contact your doctor, or go to the emergency department of your nearest hospital, "even if there are no signs of discomfort or poisoning" (Viagra CMI). An erection that lasts more than 4 hours needs "the nearest hospital emergency department" (healthdirect). The common side effects are headache, facial flushing, a blocked nose and indigestion (healthdirect). Never take sildenafil with nitrates, the medicines for angina: the drop in blood pressure can be sudden and hard to treat (healthdirect). More in what happens if you take too much Viagra?
The short answer
Once a day, never twice: one Viagra tablet in any 24 hours. Two days in a row is within that limit if the doses are 24 hours apart. If one tablet does not work, do not take a second; tell your doctor, who can change the dose or the medicine. More on doses is in our dosage guide.
