The normal dose of tadalafil depends on how you’re taking it and what it’s treating. For erectile dysfunction taken as needed, the standard starting dose is 10 mg. For daily use, it starts at 2.5 mg. These are the two most common dosing approaches, and they work quite differently in practice.
As-Needed Dosing for Erectile Dysfunction
The typical starting dose is 10 mg, taken as a single tablet roughly 30 minutes before sexual activity. You take it only when you plan to need it, and no more than once in a 24-hour period. If 10 mg works well but causes bothersome side effects, the dose can be lowered to 5 mg. If it’s not effective enough, it can be increased to 20 mg, which is the maximum for this use.
Tadalafil has a notably long half-life of about 17.5 hours, which means a single dose can improve erectile function for up to 36 hours. This is significantly longer than similar medications and is the reason tadalafil earned its “weekend pill” reputation. That long window also means there’s no need to time the dose precisely around sexual activity the way you might with shorter-acting alternatives.
Daily Low-Dose Use
The daily approach uses a much smaller dose: 2.5 mg once per day, taken at the same time each day regardless of when sexual activity might happen. This can be increased to 5 mg daily if needed. The idea is to maintain a steady, low level of the drug in your system so you don’t have to plan around taking a pill. For many people, daily dosing feels more spontaneous since the medication is always active.
If you’re treating both erectile dysfunction and an enlarged prostate (benign prostatic hyperplasia), the standard daily dose is 5 mg. This single dose addresses both conditions at once, since tadalafil relaxes smooth muscle in both the blood vessels of the penis and the prostate and bladder.
Dosing for Pulmonary Arterial Hypertension
Tadalafil is also prescribed for a serious lung condition called pulmonary arterial hypertension, where blood pressure in the arteries of the lungs is dangerously high. The dose here is much larger: 40 mg once daily, typically taken as two 20 mg tablets. Some prescribers start patients on 20 mg and work up to the full dose. People with liver or kidney problems generally start at 20 mg and increase only if they tolerate it well. These tablets should be swallowed whole, not split or crushed.
How Side Effects Change With Dose
Side effects are dose-dependent, meaning they become more common as the dose increases. The most frequent ones are headache, indigestion, back pain, muscle aches, nasal congestion, and flushing. In clinical trials, headache affected about 11% of people at 10 mg and 15% at 20 mg, compared to 5% on placebo. Indigestion followed a similar pattern: 8% at 10 mg, 10% at 20 mg, versus 1% on placebo.
Back pain and muscle aches deserve special mention because they catch people off guard. They tend to appear 12 to 24 hours after taking the medication, often as a diffuse soreness across the lower back, glutes, or thighs. This discomfort typically resolves within 48 hours without treatment. It was generally rated as mild to moderate, with severe cases reported in fewer than 5% of those who experienced it. Lying down sometimes made it worse.
These side effects are one reason prescribers start at the lower end and increase only if needed. If 10 mg works for you, there’s little reason to move to 20 mg and accept a higher likelihood of headache or stomach upset.
How Long It Takes to Work
For as-needed dosing, tadalafil is typically taken about 30 minutes before anticipated activity, though many people find it effective sooner. Because the drug stays active for up to 36 hours, the timing is forgiving. You don’t need to take it right before the moment. Food does not significantly affect absorption, so you can take it with or without a meal.
For daily dosing, the medication builds up to a steady level in your body over the first several days. The timing of your daily tablet doesn’t need to align with sexual activity at all, since the drug is continuously present.
Critical Safety Interaction With Nitrates
Tadalafil at any dose cannot be combined with nitrate medications. These are drugs commonly prescribed for chest pain (angina), including nitroglycerin and isosorbide dinitrate. Both tadalafil and nitrates lower blood pressure, and using them together can cause a dangerous, potentially life-threatening drop. This applies even to small doses of either drug. Recreational “poppers” (amyl nitrite) carry the same risk.