Both are FDA-approved oral medications for erectile dysfunction in the same drug class. But their differences in duration, dosing options, and lifestyle fit are meaningful. Here’s the physician’s guide.
By Dr. Teja V. Surapaneni, MD, MS • Board-Certified Internal Medicine (ABIM) • Licensed NV, WA, OR, WI • May 2026
Both tadalafil and sildenafil are PDE5 inhibitors. They work by blocking the enzyme phosphodiesterase type 5, which normally breaks down cGMP in the smooth muscle cells of penile blood vessels. When cGMP builds up, blood vessels relax and widen, allowing increased blood flow that facilitates an erection in response to sexual stimulation. Neither medication produces an erection without arousal — they improve the body’s natural response.
| Feature | Sildenafil | Tadalafil |
|---|---|---|
| Duration of action | 4–6 hours | Up to 36 hours (as-needed); continuous (daily) |
| Dosing options | As-needed only (25, 50, 100 mg) | As-needed (10, 20 mg) or daily (2.5, 5 mg) |
| Onset after dose | 30–60 minutes | 30–45 minutes (may be slower in some) |
| Food interaction | High-fat meals delay absorption | Not significantly affected by food |
| BPH (enlarged prostate) | Not indicated | FDA-approved for both ED + BPH |
| Back/muscle aches | Rare | Possible with as-needed dosing |
Sildenafil is typically active for 4–6 hours after taking a dose. Tadalafil has a much longer half-life — approximately 17.5 hours — so the as-needed version (10 or 20 mg) remains active for up to 36 hours. Daily tadalafil 5 mg maintains steady-state levels continuously, eliminating any need to time the medication around sexual activity.
Sildenafil’s absorption is reduced by high-fat meals — taking it after a heavy dinner can delay or diminish its effectiveness. Tadalafil is not significantly affected by food. For men who prefer not to plan meals around medication, tadalafil offers a practical advantage.
Daily tadalafil 5 mg is generally preferred for men who:
As-needed sildenafil or as-needed tadalafil are reasonable for men who prefer to take medication only when needed or have infrequent sexual activity. Some men prefer sildenafil for its lower cost; others prefer the 36-hour flexibility of as-needed tadalafil.
Both medications share a similar side effect profile: headache, facial flushing, nasal congestion, and mild visual disturbances (particularly sildenafil at higher doses). These are dose-dependent and usually mild. Because sildenafil has a shorter duration, side effects resolve more quickly. Tadalafil’s unique potential side effect is back pain or muscle aches, which occurs in some patients due to activity on PDE11 in muscle tissue — typically resolving within 24–48 hours.
PDE5 inhibitors are contraindicated in men taking nitrate medications (such as nitroglycerin for heart disease) due to the risk of severe hypotension. They should be used with caution in men with certain cardiovascular conditions. Your YourMD physician will review your complete medication list and health history during consultation.
Our men’s health program includes a live video consultation with a board-certified MD, a personalized prescription, and ongoing messaging for dose questions. Both tadalafil and sildenafil are available, as well as sublingual troches for faster onset.
Medical disclaimer: This article is for educational purposes only and does not constitute medical advice. Consult a qualified physician before starting any prescription medication. Page medically reviewed by Teja V. Surapaneni, MD, MS — Board-Certified Internal Medicine (NV, WA, OR, WI). Last reviewed: May 2026.