Viagra, Cialis and Levitra are the three best-known PDE5 inhibitors — prescription pills that treat erectile dysfunction by boosting blood flow to the penis during sexual arousal. They work in very similar ways with comparable success rates, so the practical choice usually comes down to how fast each one works, how long its window lasts, and whether food and timing matter. All three are prescription-only and share one critical safety rule: they must never be combined with nitrate heart medicines.
There's no single "best" — for most men the three are broadly comparable, so the honest way to choose is by how fast and how long you want it to work. Sildenafil (Viagra) is taken shortly before sex and works best on an empty stomach, because a high-fat meal delays it; vardenafil (Levitra) is similar but can be taken with or without food; tadalafil (Cialis) stands out for its long window — its FDA label says it can improve erectile function up to about 36 hours after a dose — and it also comes as a low once-daily option. One safety rule applies to all three: PDE5 inhibitors must never be combined with nitrate heart medicines (such as nitroglycerin or isosorbide dinitrate/mononitrate) or recreational "poppers," because the combination can cause a sudden, dangerous drop in blood pressure. These are prescription-only medicines: which one and what dose is decided by your prescriber — do not start, stop, or switch on your own. This is general information, not medical advice — ask your doctor or pharmacist.
| Viagra sildenafil | Cialis tadalafil | Levitra vardenafil | |
|---|---|---|---|
| Active ingredient | Sildenafil Citrate | Tadalafil | Vardenafil Hydrochloride |
| Our rating | 68/100 | Not yet rated | Not yet rated |
| Typical price | $0.11 /mL | ~$4.64 /30 | ~$85.98 /30 |
| Onset | About 1 hour before sex (can be taken any time from 4 hours to 30 minutes before) | At least 30 minutes before sex | About 60 minutes before sex |
| How long it lasts | Short-acting — a single as-needed dose, taken no more than once every 24 hours | Long — FDA label: improves erectile function up to about 36 hours after a dose; daily-dose option available | Short-acting — a single as-needed dose, taken no more than once every 24 hours |
| Take with food? | Yes, but best on an empty stomach — a high-fat meal delays how fast it works | With or without food | With or without food |
| Prescription? | Yes — prescription-only | Yes — prescription-only | Yes — prescription-only |
| Good to know | Short-acting and taken close to sex; works best on an empty stomach, because a high-fat meal makes it take longer to work. | The long-lasting option — its FDA label documents an effect up to about 36 hours; also comes as a low once-daily dose. | Short-acting like Viagra, but can be taken with or without food. |
Ratings are our independent FDA recall-safety score. General information, not medical advice.
Viagra (sildenafil)
Short-acting and taken close to sex; works best on an empty stomach, because a high-fat meal makes it take longer to work.
Cialis (tadalafil)
The long-lasting option — its FDA label documents an effect up to about 36 hours; also comes as a low once-daily dose.
Levitra (vardenafil)
Short-acting like Viagra, but can be taken with or without food.
All three are similarly effective PDE5 inhibitors, so pick by practical fit: Viagra (sildenafil) or Levitra (vardenafil) if you prefer a short-acting pill taken about an hour before sex (take Viagra on an emptier stomach, since a high-fat meal slows it); Cialis (tadalafil) if you'd rather have a much longer window — its FDA label documents an effect up to roughly 36 hours — or a low daily dose. The critical safety point applies to all of them: PDE5 inhibitors must never be taken with nitrate medicines (such as nitroglycerin or isosorbide dinitrate/mononitrate) or recreational "poppers" — the combination can cause a sudden, dangerous drop in blood pressure, and the Cialis FDA label lists nitrate use as a contraindication. Tell your doctor about heart disease, chest pain, low blood pressure, or any nitrate use before starting. These are prescription-only; which drug and dose is your prescriber's decision — do not start, stop, or switch on your own. As an independent ratings site, pharmaranks adds its own FDA recall-safety score and a live NADAC cost-per-dose on each product page so you can weigh safety history and price too. This is general information, not medical advice — ask your doctor or pharmacist.