What is the difference between 50 mg and 100 mg Viagra? Only the amount of sildenafil: the 100 mg tablet holds twice as much of the same medicine. 50 mg is the usual starting dose; 100 mg is the maximum, for men in whom 50 mg is not enough (EMA). Both are taken the same way, one tablet about an hour before sex and no more than one dose a day, and "Your doctor will decide the correct dose for you depending on your condition and response" (Viagra CMI).
Is 100 mg stronger than 50 mg?
Yes, in the blood, and a little in the result. Within the 25 to 100 mg range, the amount of sildenafil in the blood rises in proportion to the dose (EMA product information), so 100 mg gives about twice the level of 50 mg. The gain in effect is smaller. In the fixed-dose studies behind the European label, these were the shares of men who said their erections improved:
| Dose | Men reporting improved erections |
|---|---|
| Placebo | 25% |
| 25 mg | 62% |
| 50 mg | 74% |
| 100 mg | 82% |
Source: EMA product information, section 5.1.
Viagra is on the Australian register in three strengths, 25, 50 and 100 mg (ARTG), and 100 mg is the top of that range.
Does 100 mg work faster or last longer?
Not according to the label. The leaflet gives one timing for every strength: take it about one hour before sex; it normally takes "between half an hour and one hour" to start working (Viagra CMI), and its effects can last for up to 4 hours (healthdirect). The half-life, 3 to 5 hours, is not given by strength either (EMA product information). Whatever the dose, it works only with sexual arousal, and a heavy meal can slow it down; more in empty stomach or after eating?
Does 100 mg cause more side effects?
The label does not give side-effect rates by strength, but it treats side effects as a reason to go down: the dose may be increased to 100 mg or decreased to 25 mg "based on efficacy and tolerability" (EMA product information). The common side effects of ED medicines are headache, facial flushing, a blocked nose and indigestion or reflux (healthdirect). If they bother you on 100 mg, the label allows stepping back to 50 mg. Above 100 mg the answer is clear: "Doses of 200 mg did not result in increased efficacy but the incidence of adverse reactions ... was increased" (EMA product information); more in is it safe to take 200 mg of Viagra?
Which strength do men start on?
Most start on 50 mg. The product information suggests considering 25 mg instead for men with severe kidney impairment or with liver impairment such as cirrhosis, for men taking medicines that slow the breakdown of sildenafil (CYP3A4 inhibitors), and for men on an alpha-blocker, who should be stable on it first. Older age is not on that list: "Dose adjustments are not required in elderly patients (≥ 65 years old)" (EMA product information). Whether 100 mg is too much for you is covered in is 100 mg of sildenafil or Viagra too much?
Are two 50 mg tablets the same as one 100 mg tablet?
They hold the same amount of sildenafil, but that is not how the dose is written. The Australian leaflet's dose is "one 25 mg tablet, one 50 mg tablet, or one 100 mg tablet per day" (Viagra CMI), and the package leaflet says "You should not take more tablets than your doctor tells you to" (EMA package leaflet). A second 50 mg tablet later in the day is a second dose, which the one-dose-a-day rule excludes; see can I take Viagra twice in one day? Halving a 100 mg tablet to make 50 mg is not what the leaflet says either: it says to swallow the tablet whole; see can Viagra pills be split in half?
What if 50 mg does not work?
Tell your doctor rather than raising the dose yourself. "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: arousal, the hour before sex, a heavy meal. What a first dose is like is in what to expect when taking Viagra for the first time. At any strength, never take sildenafil with nitrates, the medicines for angina (healthdirect).
The short answer
100 mg Viagra is twice the sildenafil of 50 mg, with a modest gain in effect (82% against 74% in the studies) and no change in timing. 50 mg is where most men start; 100 mg is the ceiling, reached on your doctor's advice, one tablet a day at most. More on doses is in our dosage guide.
