Can I Take 40 mg of Tadalafil? Dose Limits and Stronger Options

Tadalafil helps millions of men get and keep a firm erection, but doubling the usual dose is not always the answer. Learn the science-backed ceiling, why 40 mg is reserved for another illness, and what to try when 20 mg no longer cuts it.

Reviewed for general education · Updated October 2026 · 11 min read

The maximum FDA-approved dose of tadalafil (brand Cialis) for erectile dysfunction is 20 mg taken no more than once every 24 hours, because higher amounts do not add meaningful benefit but do raise the chance of headache, low blood pressure, and other side effects. A 40 mg strength exists only for pulmonary arterial hypertension under the brand Adcirca and should not be used for erections. If 20 mg is not working, evidence-based alternatives include switching timing, trying a different phosphodiesterase-5 inhibitor, or moving to intracavernosal injection therapy, or a needle-free compounded combination such as Rx.com’s sublingual Quad Mix.

Tadalafil’s half-life is about 17.5 hours, so two 20 mg tablets within a day effectively equal a single 40 mg exposure. (ncbi.nlm.nih.gov)
Headache occurs in 15 % of men using 20 mg, compared with 5 % on placebo. (dailymed.nlm.nih.gov)
The FDA has never approved 40 mg tadalafil for erectile dysfunction; the 40 mg dose is labeled for pulmonary arterial hypertension as two 20 mg Adcirca tablets once daily. (pubmed.ncbi.nlm.nih.gov)
About 18 million U.S. men live with erectile dysfunction, and prevalence rises to 70 % by age 70. (pubmed.ncbi.nlm.nih.gov)
Options when 20 mg fails include switching to sildenafil 100 mg, daily tadalafil 5 mg, or physician-guided injection therapy. (auajournals.org)

Bottom line: For ED, 20 mg once per day is the legal and practical ceiling for tadalafil-doubling the dose risks harm without proven gain.

What Tadalafil Is and How It Works

Tadalafil is a phosphodiesterase-5 (PDE5) inhibitor that relaxes smooth muscle in penile arteries, allowing more blood to flow in and create a firm erection when a man is sexually stimulated. The drug reaches peak levels about two hours after swallowing and maintains activity for up to 36 hours thanks to its 17.5-hour half-life. (ncbi.nlm.nih.gov) That long window is why tadalafil is nicknamed “the weekend pill.” For daily use, lower 2.5- or 5-mg tablets keep a steady level for men who prefer spontaneity.

Tadalafil is sold generically and under several brands, including Cialis for erectile dysfunction and benign prostatic hyperplasia, and Adcirca for pulmonary arterial hypertension. You can review full prescribing details on the tadalafil drug page or in our tadalafil dosage guide.

Why 40 mg Is Not an Approved ED Dose

Clinical trials found no additional erectile benefit above 20 mg, while side-effect rates continued to climb, so regulators capped the as-needed ED dose at 20 mg. In pivotal phase 3 studies, erection scores on the International Index of Erectile Function improved similarly with 10 mg and 20 mg, and doses beyond 20 mg were not pursued. (pubmed.ncbi.nlm.nih.gov)

Adcirca 40 mg is a different indication. Tadalafil 40 mg (two 20 mg tablets once daily) is FDA-approved to lower pulmonary artery pressure, not to treat erection problems. (pubmed.ncbi.nlm.nih.gov) Using Adcirca off-label for ED would double systemic exposure, potentially causing:

Sharper blood-pressure drops leading to dizziness or fainting
Higher rates of muscle and back pain
More pronounced facial flushing and nasal congestion
Rare but serious risks such as priapism (erection lasting >4 hours) and sudden vision loss

Indication	Usual Dose	Maximum FDA-Approved Dose
Erectile dysfunction, as needed	10 mg 30 min before sex	20 mg once every 24 h
Erectile dysfunction, daily	2.5 mg–5 mg once daily	5 mg once daily
Benign prostatic hyperplasia	5 mg once daily	5 mg once daily
Pulmonary arterial hypertension (Adcirca)	40 mg once daily	40 mg once daily

How Common Is Needing More Than 20 mg?

Roughly one in five men with erectile dysfunction report sub-optimal response to first-line PDE5 inhibitors, but true non-responders to tadalafil 20 mg are uncommon. Across eight placebo-controlled trials, 80 % of men on 20 mg achieved erections firm enough for intercourse versus 35 % on placebo. (pmc.ncbi.nlm.nih.gov) Most “non-response” stems from wrong timing, heavy meals, alcohol, or unmanaged health conditions rather than inadequate drug strength.

Population studies estimate that 18 million U.S. men live with ED and prevalence reaches 70 % by age 70. (pubmed.ncbi.nlm.nih.gov) Only a fraction will ultimately need advanced therapy beyond oral pills.

How to Get Better Results Without Exceeding 20 mg

Before jumping to stronger prescriptions, optimize how you take tadalafil. Small adjustments restore efficacy in many men:

Take on an empty stomach: Fatty or heavy meals slow absorption by up to 90 minutes.

Time it right: Levels peak two hours after swallowing. Plan intimacy 1–3 hours post-dose, not immediately.

Limit alcohol: More than five units can drop blood pressure further and weaken erections.

Try daily 5 mg: Low-dose daily therapy maintains a steady concentration and helps men with performance anxiety or unpredictable schedules.

Address underlying conditions: High blood pressure, diabetes, and low testosterone blunt PDE5 inhibitor response. Managing these improves success.

Explore more practical tips in our daily vs. as-needed tadalafil comparison.

Stronger Options If 20 mg Still Fails

When proper use of 20 mg tadalafil is inadequate, evidence supports three main escalation paths.

Therapy	Typical Maximum Dose	Onset	Duration
Sildenafil	100 mg	30–60 min	4–6 h
Vardenafil	20 mg	30–60 min	4–6 h
Avanafil	200 mg	15–30 min	4–6 h
TriMix injection	Individualized	5–15 min	30–90 min

Switch to another PDE5 inhibitor: Some men metabolize sildenafil or avanafil differently and gain stronger firmness at their respective max doses. (auajournals.org)

Combine daily tadalafil with on-demand sildenafil: A small crossover study found higher success than either strategy alone, though data remain limited. (academic.oup.com)

Move to intracavernosal therapy: TriMix and similar injection blends bypass oral absorption and work in up to 90 % of men who fail pills. Treatment requires urology guidance but offers dose flexibility.

Vacuum devices and penile implants: Mechanical solutions can restore sexual confidence when medications fail or are contraindicated.

Our guide to the best ED telehealth options explains how online visits can evaluate these next-step treatments discreetly.

Should You Try 40 mg or Call Your Doctor?

Check the column that fits your situation:

✅ Stay at 20 mg

Erections are reliable most of the time
Side effects are mild or absent
You can plan sex 1–3 hours after dosing
No conflicting medications (nitrates, alpha-blockers)

🏥 See a Doctor

Still no erection after three properly timed attempts
Severe headache, dizziness, or vision changes
You have heart disease and take nitrates
Kidney or liver impairment
Priapism (erection >4 hours) at any dose
Considering any dose above 20 mg without supervision

Drug Interactions and Health Conditions That Raise Risk

Tadalafil intensifies the blood-pressure-lowering effect of nitrates and alpha-blockers, which can trigger dangerous hypotension. The label forbids any PDE5 inhibitor within 48 hours of short-acting nitroglycerin or 14 days of chronic nitrate therapy. (dailymed.nlm.nih.gov)

CYP3A4 inhibitors such as ketoconazole and ritonavir can triple tadalafil levels. In these cases, the FDA advises no more than 10 mg every 72 hours. (dailymed.nlm.nih.gov)

Significant renal or hepatic impairment also calls for lower doses or avoidance. See full details on the tadalafil label and our explainer on Cialis dose adjustments.

🚨 When to Contact Your Healthcare Provider

Contact your doctor immediately if you experience any of the following:

Chest pain or shortness of breath - could signal dangerous low blood pressure
Sudden vision loss - possible non-arteritic ischemic optic neuropathy
Hearing decrease or ringing in ears - rare but documented adverse effect
Priapism (erection lasting >4 hours) - can cause permanent damage
Severe back or muscle pain unrelieved by over-the-counter analgesics
Dizziness or fainting especially with alcohol or antihypertensives
Rash, hives, or swelling of lips/tongue - signs of allergic reaction
Persistent headache or blurred vision after dosing

Scientific References

Frequently Asked Questions

Is it safe to split two 20 mg tablets 12 hours apart?

No. Because tadalafil’s half-life is 17.5 hours, taking two doses in one day approximates a 40 mg exposure and increases side-effect risk. Always wait a full 24 hours between as-needed doses unless your doctor instructs otherwise.

Does insurance cover higher doses of tadalafil?

Most U.S. plans cover generic 5 mg and 20 mg tablets. A 40 mg prescription for pulmonary hypertension is covered only if you meet strict criteria for that condition, not for ED.

Can I crush 20 mg tablets into a drink to take half now, half later?

Crushing voids the scored design and risks inaccurate dosing. If you need flexible doses, ask your pharmacist for 5 mg tablets instead.

Will higher doses work better if I have diabetes?

Men with diabetes often need careful timing and glucose control rather than larger doses. Switching to a different PDE5 inhibitor or injection therapy is usually more effective than exceeding 20 mg.

How does tadalafil compare with sildenafil at their max strengths?

Sildenafil 100 mg acts faster but lasts 4–6 hours, while tadalafil 20 mg starts slower yet lasts up to 36 hours. Neither should be exceeded without medical advice.

Can telehealth doctors prescribe tadalafil online?

Yes. Licensed U.S. providers can evaluate ED remotely and e-send a prescription to your local pharmacy. See our guide on telehealth ED prescribing for details.

How much does tadalafil cost without insurance?

Generic 20 mg tablets often range from $0.70 to $3 each. You can compare cash prices on Rx.com and download a free discount card to save 55–85 % at local pharmacies.