Tadalafil 20 mg: How Long It Lasts, Daily Dosing and BPH

How long does tadalafil last?

The as-needed studies measured erectile function against placebo out to 36 hours after the tablet. That window is why men call it the weekend pill. It is not a 36-hour erection. Sexual stimulation is still required, and one tablet a day is the cap.¹

The mean terminal half-life is 17.5 hours in healthy subjects. Most of the dose leaves as metabolites in the feces (about 61%) and the rest in the urine (about 36%).¹

Food does not set the clock. The label says tadalafil tablets may be taken without regard to food.¹

Daily tadalafil versus as-needed 20 mg

As-needed use starts at 10 mg before sex, then 20 mg or 5 mg depending on how it works and how it feels. Daily use is a different ladder: 2.5 mg at about the same time each day, then 5 mg if needed. The 20 mg tablet is not the daily dose.¹

Daily tadalafil ignores the hour of sex. As-needed tadalafil is timed to a plan, then can still work the next calendar day because of that 36-hour window.¹

The 5 mg tablet for an enlarged prostate

For benign prostatic hyperplasia the labeled dose is 5 mg, taken at about the same time every day. The same 5 mg line is used when a man has both ED and BPH.¹

That is a once-daily tablet, not a 20 mg swallow before sex. Pulmonary arterial hypertension uses a different tadalafil product (Adcirca) at other milligram totals. Those tablets are not swapped with Cialis strengths on this page.¹

Tadalafil side effects that show up later

The reactions seen in at least 2% of men were headache, dyspepsia, back pain, myalgia, nasal congestion, flushing, and pain in a limb.¹

On 20 mg, headache was 15%, dyspepsia 10%, and back pain 6%. In the eight 12-week as-needed studies, 3.1% of men on 10 or 20 mg stopped because of an adverse event, against 1.4% on placebo. Mean age in those rooms was 59 (range 22 to 88).¹

Back pain and muscle ache can start hours after the dose and last a day or two. An erection lasting more than 4 hours, or a sudden drop in vision or hearing, means stop and get help.¹

Nitrates, alcohol and other drugs

Nitrates in any form, including recreational amyl nitrite, are a stop. Tadalafil can add to the blood-pressure drop from those drugs.¹

Alpha-blockers and other blood-pressure tablets can stack the same way. A man already stable on an alpha-blocker is not started on 20 mg.¹

Alcohol can deepen a blood-pressure drop. Grapefruit can raise tadalafil levels. The label still allows the tablet with a meal.¹

What thirty tadalafil tablets cost with a coupon

GoodRx says Cialis is not covered by most Medicare and insurance plans. On 08/24/26, thirty generic 20 mg tablets listed at $14.24 with a coupon against $1,620.55 average retail. Thirty 5 mg tablets were $13.70 against $365.38. Thirty 10 mg tablets were $18.72 against $2,171.45. Thirty 2.5 mg tablets were $16.99 against $313.05.²

Sources

1. DailyMed: Tadalafil tablet prescribing information
2. GoodRx: Cialis and tadalafil prices, updated 08/24/26
3. FDA BeSafeRx: Considering an online pharmacy?

Consultation

Your questions, answered

Answered by Dr. Ethan Cole, MD · Urology & men's sexual health

Answers follow the U.S. tadalafil prescribing information.

Can I take tadalafil every day?

Yes, but not as a 20 mg tablet. Daily use starts at 2.5 mg at about the same hour each day, then 5 mg if that is not enough. The 20 mg strength is the as-needed ceiling, once in 24 hours.

I ate a steak and then took 20 mg. Did I waste it?

The label says the tablet may be taken with or without food. A heavy meal is not the problem it is with sildenafil. If the dose still felt weak, the next question is whether 10 mg was the right start, not whether the plate blocked it.

Is generic tadalafil the same as Cialis?

Same active ingredient and the same four strengths: 2.5, 5, 10 and 20 mg. Adcirca is a different tadalafil product for pulmonary arterial hypertension and is not a Cialis substitute.

Can I have a beer?

Alcohol can add to tadalafil's drop in blood pressure. The label does not set a drink count. A nitrate spray or a recreational nitrite is a hard no, beer or not.

The pharmacy said thirty 20 mg tablets would be over a thousand dollars.

That is in range for the undiscounted retail line. GoodRx's 08/24/26 table put average retail for thirty 20 mg tablets at $1,620.55 and the coupon at $14.24. Most Medicare and insurance plans do not cover it, so the coupon is often the cash price that actually prints.

General education from a clinician, not personal medical advice. Bring your own history to your own prescriber.