Viagra, Cialis, and Levitra all treat erectile dysfunction by the same basic mechanism, and clinical effectiveness rates between them are close enough that no single one is objectively “best.” The real differences that actually matter for choosing between them come down to how fast each one kicks in, how long it lasts, how food and timing affect it, and how each fits into a person’s specific life and health situation — not which one works better in a lab.
The Short Answer
Viagra (sildenafil) is a solid default for occasional use with a well-established track record and low generic cost, but it needs to be taken on a relatively empty stomach and works for a shorter window. Cialis (tadalafil) lasts far longer — up to 36 hours — and isn’t affected much by food, making it the better fit for spontaneity or more frequent use, and it’s also available as a low daily dose. Levitra (vardenafil) sits in between on duration but is less affected by food than Viagra and has shown an advantage for men whose ED is related to diabetes. All three are similarly effective overall; the right choice usually comes down to lifestyle and health factors rather than raw effectiveness.
How These Medications Work
All three drugs belong to a class called PDE5 inhibitors. They work by blocking an enzyme that normally restricts blood flow, which allows blood vessels in the penis to relax and fill with blood more easily during arousal. None of them cause an erection on their own — sexual stimulation is still required for any of them to work. Because they all work through the same core mechanism, side effects and precautions overlap heavily across the three, and the differences that matter most come down to pharmacokinetics: how fast each drug is absorbed, how long it stays active, and how food interacts with it.
Viagra (Sildenafil)
Viagra was the first oral ED medication and remains the most recognized by name. It typically starts working within 30 to 60 minutes and lasts about 4 to 6 hours. It comes in 25mg, 50mg, and 100mg doses, with 50mg as the typical starting point. Taking it on a full stomach, especially after a high-fat meal, meaningfully delays how quickly it starts working, which is one of its more practical drawbacks. As a generic (sildenafil), it’s typically one of the least expensive options, often just a few dollars per pill.
Cialis (Tadalafil)
Cialis takes a bit longer to kick in — usually 30 minutes to 2 hours — but lasts dramatically longer, up to 36 hours, which has earned it the nickname “the weekend pill.” Food has minimal effect on how it’s absorbed, unlike Viagra. It’s available as an as-needed dose (typically 10mg or 20mg) or as a low daily dose (2.5mg to 5mg) for men who prefer not to plan around sexual activity at all. Tadalafil also has an approved use for treating symptoms of an enlarged prostate, which makes it a common choice for older men managing both conditions at once. Generic tadalafil is typically similarly priced to generic sildenafil.
Levitra (Vardenafil) — and a Quick Note on Availability
Levitra works similarly to Viagra: onset around 30 minutes, duration around 4 to 5 hours, and it’s somewhat less affected by food than Viagra, though high-fat meals can still slow absorption. One notable advantage shown in research is stronger relative effectiveness for men whose erectile dysfunction is related to diabetes, where vascular changes can make some other options less effective.
Worth knowing before comparison-shopping by brand name: the brand-name Levitra tablet has been discontinued in many markets, and what’s available today is almost always generic vardenafil (sometimes still sold under the related brand Staxyn as an orally-dissolving tablet). Functionally it’s the same medication — this is just a naming detail that trips up a lot of people searching by the original brand name.
Side-by-Side Comparison
| Viagra (Sildenafil) | Cialis (Tadalafil) | Levitra (Vardenafil) | |
| Onset time | 30-60 minutes | 30 min-2 hours | 25-60 minutes |
| Duration | 4-6 hours | Up to 36 hours | 4-5 hours |
| Typical strengths | 25mg, 50mg, 100mg | 2.5mg, 5mg, 10mg, 20mg | 5mg, 10mg, 20mg |
| Food interaction | High-fat meals delay onset | Minimal effect | Less affected than Viagra |
| Daily-dose option | No | Yes (2.5-5mg) | No |
| Generic cost | Low (a few dollars/pill) | Low (a few dollars/pill) | Moderate |
Side Effects Compared
All three share a similar side effect profile since they work the same way, but the frequency of specific side effects varies slightly:
- Headache: reported by roughly 16% of Viagra users, 11% of Cialis users, and 15% of Levitra users
- Flushing: common across all three, generally mild and temporary
- Back or muscle pain: reported more often with Cialis, in around 6% of users, likely related to its longer duration in the body
- Vision changes, including a blue tinge to vision: specifically associated with Viagra more than the other two
- Upset stomach or indigestion: reported across all three, generally mild
None of the three are safe to combine with nitrate medications (often prescribed for chest pain or heart conditions), and all three carry the same warning about seeking immediate medical attention for an erection lasting more than 4 hours.
Which One Fits Your Situation
| Your Situation | Reasonable Starting Point |
| First time trying an ED medication, cost-conscious | Generic sildenafil (Viagra) |
| Want spontaneity without planning meals or timing | Cialis (tadalafil), including the daily low-dose option |
| Sexual activity happens more than twice a week | Daily tadalafil |
| Diabetes is a contributing factor to ED | Vardenafil (Levitra), worth discussing with a doctor |
| Also dealing with an enlarged prostate | Cialis (tadalafil), which is approved for both |
| Want the fastest possible onset | Levitra or Viagra taken on an empty stomach |
Can You Switch Between Them?
Yes — it’s common and generally safe to try a different PDE5 inhibitor if one isn’t working well, as long as it’s not combined with another one at the same time. Response to these medications varies by individual, and it’s not unusual for someone to get better results from one over another even though they work the same way. A doctor can help adjust dosage or switch medications if the first option tried isn’t giving the expected results, rather than assuming none of them will work.
When to Talk to a Doctor
It’s worth a doctor’s visit before starting any of these medications, particularly for men with heart conditions, low or high blood pressure, or those taking nitrates, alpha-blockers, or other medications that can interact. It’s also worth a follow-up conversation if the first medication tried at an appropriate dose doesn’t work after several attempts — that’s a common and normal reason to try a different option or explore other ED treatments entirely, not a sign that nothing will work.
Frequently Asked Questions
Which lasts longer, Viagra or Cialis?
Cialis lasts significantly longer — up to 36 hours, compared to 4 to 6 hours for Viagra. This is the single biggest practical difference between the two.
Is Levitra still available, or has it been replaced?
The original Levitra brand has been discontinued in many markets. The medication itself, vardenafil, is still widely available as a generic, and functions the same way.
Can I take Viagra and Cialis together?
No. Combining two PDE5 inhibitors doesn’t improve results and significantly increases the risk of side effects, including a dangerous drop in blood pressure.
Which ED medication has the fewest side effects?
Reported rates are similar across all three, though Cialis has a somewhat lower reported headache rate and Levitra has a lower rate of vision-related side effects compared to Viagra.
Key Takeaways
- All three medications work the same way and have similar overall effectiveness — the real differences are onset, duration, food interaction, and personal fit
- Cialis lasts up to 36 hours and has a daily-dose option, making it the best fit for spontaneity or frequent use
- Viagra is well-established and typically the least expensive, but needs to be taken away from high-fat meals
- Levitra (vardenafil) has shown an advantage for diabetes-related ED, and the original brand has largely been replaced by generic vardenafil
- Switching between them is common and safe if one isn’t working — just never combine two at once
