Where 20 mg sits on the tadalafil label
Tadalafil is one drug with four labeled uses, and 20 mg shows up in two of them.
| Use | Dose on the FDA label | How it is taken |
|---|---|---|
| Erectile dysfunction, as needed | Start at 10 mg; range 5 to 20 mg | Before sex, no more than once a day |
| Erectile dysfunction, once daily | 2.5 mg, may increase to 5 mg | Every day, whatever the timing of sex |
| Enlarged prostate (BPH), or ED with BPH | 5 mg | Every day at about the same time |
| Pulmonary arterial hypertension (sold as Adcirca) | 40 mg, taken as two 20 mg tablets | Once a day |
The Cialis label calls 20 mg a day the maximum recommended human dose. The same 20 mg tablet is the unit of the Adcirca dose for pulmonary arterial hypertension, and the Cialis patient leaflet says not to take Cialis and Adcirca together.
FDA approved the first generic tadalafil, from Teva, on May 22, 2018, in 2.5, 5, 10 and 20 mg, and found it therapeutically equivalent to Cialis. Teva says it launched the generic on September 27, 2018. Brand Cialis now comes in 5, 10 and 20 mg; generic makers still supply 2.5 mg.
How long 20 mg lasts
- Onset and peak. Blood levels peak between 30 minutes and 6 hours after a dose, 2 hours at the median. In the label’s timing study, 52% of men on 20 mg had a successful erection within 30 minutes, against 38% on 10 mg and 35% on placebo.
- Duration. The label says erections improve for up to 36 hours. In one study of a single 20 mg dose, 61% of men reported at least one successful attempt at intercourse 22 to 26 hours later, against 37% on placebo, and 64% at 33 to 39 hours, against 37%.
- Half-life. Tadalafil’s half-life is 17.5 hours in healthy men, and the patient leaflet notes that some of a single tablet remains in your body for more than 2 days.
- Food. Food does not change how much tadalafil you absorb or how fast, so it can be taken with or without a meal.
- Age. Men 65 and older had 25% higher exposure, and the label makes no dose change for age alone.
Tadalafil has no effect without sexual stimulation, because arousal starts the release of nitric oxide that its action depends on.
20 mg or 10 mg: what the extra 10 mg buys
The label’s approach is to start at 10 mg and adjust by how well it works and how well you tolerate it. A pooled analysis of 11 placebo-controlled trials in 2,102 men measured the step. Scores on the erectile function domain of the IIEF questionnaire rose 6.5 points from baseline on 10 mg and 8.6 points on 20 mg, and the other two measures looked like this:
| Placebo | 10 mg | 20 mg | |
|---|---|---|---|
| Intercourse attempts that succeeded | 31% | 58% | 68% |
| Men reporting improved erections | 33% | 71% | 84% |
Side effects rise with the dose as well. In the label’s pooled trials, headache affected 11% of men on 10 mg and 15% on 20 mg, and indigestion 8% and 10%. In the label’s trial of men with diabetes, 10 mg and 20 mg gave similar results. On average the gain from 10 to 20 mg is modest, and the label starts most men at 10 mg.
When the label caps tadalafil below 20 mg
| If you | The as-needed limit on the label |
|---|---|
| Have moderately reduced kidney function (creatinine clearance 30 to 50 mL/min) | Start at 5 mg; at most 10 mg, no more than once every 48 hours |
| Have severely reduced kidney function (under 30 mL/min) or are on dialysis | At most 5 mg, no more than once every 72 hours |
| Have mild or moderate liver impairment (Child-Pugh A or B) | No more than 10 mg once a day |
| Have severe liver impairment (Child-Pugh C) | Not recommended |
| Take a strong CYP3A4 inhibitor such as ketoconazole or ritonavir | At most 10 mg, no more than once every 72 hours |
| Take an alpha-blocker | Be on a stable dose first, then start tadalafil at the lowest dose |
| Use any nitrate, including “poppers,” or riociguat | Do not take tadalafil |
The interacting-drug limits come from measured exposure. Ketoconazole raised the exposure of a single 20 mg dose by 312% and ritonavir by 124%. The label expects erythromycin, itraconazole and grapefruit juice to raise it too, and the patient leaflet asks men to mention antibiotics such as clarithromycin and erythromycin.
For nitrates, the label sets a waiting period: if a nitrate is ever needed in an emergency, at least 48 hours should pass after your last dose of tadalafil. In the label’s nitroglycerin study, the interaction was present through 24 hours and absent by most measures at 48 hours.
Alcohol adds its own limit. Five or more drinks with tadalafil can raise your heart rate and drop your standing blood pressure, with dizziness and headache. The label also says tadalafil is not recommended after a heart attack in the past 90 days or a stroke in the past 6 months, among other heart conditions.
Side effects at 20 mg
These are from the label’s eight pooled placebo-controlled trials of as-needed use.
| Side effect | Placebo | 10 mg | 20 mg |
|---|---|---|---|
| Headache | 5% | 11% | 15% |
| Indigestion (dyspepsia) | 1% | 8% | 10% |
| Back pain | 3% | 5% | 6% |
| Muscle aches | 1% | 4% | 3% |
| Nasal congestion | 1% | 3% | 3% |
| Flushing | 1% | 3% | 3% |
| Pain in a limb | 1% | 3% | 3% |
Back pain and muscle aches usually start 12 to 24 hours after a dose and fade within 48 hours. In the trials, 3.1% of men on 10 or 20 mg stopped because of side effects, against 1.4% on placebo.
Three rare effects call for action right away: an erection lasting more than 4 hours needs emergency care, and sudden loss of vision or hearing means stopping tadalafil and getting medical help promptly.
Can you split a 20 mg tablet?
The current Cialis label opens its dosing section with one line: “Do not split CIALIS tablets; entire dose should be taken.” Generic labels carry the same instruction, and the 20 mg generic tablets described on DailyMed are plain on one side, with no score line described. FDA’s guidance on tablet splitting explains why it matters: a tablet approved for splitting is scored and says so in its labeling, and without that, FDA has not checked that two halves carry the same amount of drug.
If a lower dose suits you better, tadalafil comes in 10, 5 and 2.5 mg tablets, so the dose you need can be prescribed directly.
Can you take 20 mg every day?
The label allows as-needed tadalafil up to once a day, at up to 20 mg. Its once-daily ED regimen is a different plan: 2.5 to 5 mg taken every day, which keeps a steady level of tadalafil in your body so the timing of sex stops mattering.
Two meta-analyses compared the approaches. Daily tadalafil scored 1.82 points higher on the erectile function scale than on-demand dosing at 12 weeks, a gap the authors said may not be clinically significant, and a second analysis of trials lasting at least 24 weeks found a 1.24-point difference. A pooled analysis of Lilly’s trial database found no group of men that clearly did better on one schedule than the other. More on how tadalafil compares with sildenafil is in sildenafil vs tadalafil.
Fast-dissolve and troche forms
No orally disintegrating, film or sublingual tadalafil product is listed on DailyMed. PepScribe’s fast-dissolve forms are compounded. The published human data come from manufactured films studied abroad. A 20 mg orodispersible film matched the tablet’s exposure, with the same 2.5-hour median time to peak, and a review of these formats found they share the tablets’ pharmacokinetics while adding discretion, since no water is needed. One film failed to match the tablet when taken after a meal. We found no published human study of a compounded tadalafil troche.
What a fast-dissolve form offers, then, is a way to take tadalafil without swallowing a tablet or reaching for water. PepScribe’s compounded options are on the fast-dissolve tadalafil page.
How to get tadalafil through PepScribe
- Start the free online visit at /book/tadalafil and answer questions about your health, your heart and the medicines you take.
- A licensed clinician reviews your answers, screens for nitrates and the other interactions above, and decides with you on the dose and whether daily or as-needed dosing fits.
- Your tadalafil ships in plain packaging, as an FDA-approved generic tablet or a compounded fast-dissolve form, and you can message the care team with questions.
Plan details are on the tadalafil page.
Frequently asked questions
How long does tadalafil 20 mg last?
The label says a dose improves erections for up to 36 hours. Its half-life is 17.5 hours, and some of a single tablet stays in the body for more than 2 days.
How long before sex should I take tadalafil 20 mg?
The label says at least 30 minutes before. Blood levels peak at a median of 2 hours, and in the label’s study 52% of men on 20 mg had a successful erection within 30 minutes.
Is 20 mg of tadalafil too much?
It is the highest as-needed dose on the label, and most men start at 10 mg. The label caps the dose lower for reduced kidney or liver function and for men taking strong CYP3A4 inhibitors.
Can I take tadalafil 20 mg every day?
As-needed tadalafil can be taken up to once a day. The label’s once-daily ED regimen uses 2.5 to 5 mg instead, which keeps a steady level in your body.
Can I cut a 20 mg tadalafil tablet in half?
The label says not to split the tablets. Tadalafil comes in 2.5, 5 and 10 mg tablets, so a lower dose can be prescribed directly.
Can I drink alcohol with tadalafil 20 mg?
Heavy drinking is the concern. Five or more drinks with tadalafil can cause dizziness, a faster heart rate and a drop in blood pressure when you stand.
What is the difference between tadalafil 5 mg and 20 mg?
5 mg is the usual once-daily dose for an enlarged prostate, the upper once-daily dose for ED and the lowest as-needed dose. 20 mg is the highest as-needed dose for ED.
