Erectile dysfunction (ED) is common, and it is nothing to be embarrassed about. If you have looked into treatment, you have probably seen two names come up again and again: sildenafil and tadalafil. Both are prescription medicines, and both may help many men with ED. They also have some practical differences.
This guide compares them in general terms. It is not medical advice, and a licensed clinician decides which option, if any, is right for you.
How these medications work
Sildenafil and tadalafil belong to a group of medicines called PDE5 inhibitors. In simple terms, they may help increase blood flow to the penis when you are sexually aroused.
It is important to understand that these medicines do not cause an erection on their own. Sexual stimulation is still needed. They also do not increase sex drive, and they do not treat the underlying causes of ED, such as heart disease or diabetes.
Sildenafil is the active ingredient in Viagra®. Tadalafil is the active ingredient in Cialis®. Both are also available as generic medications.
Key differences at a glance
| Feature | Sildenafil | Tadalafil |
|---|---|---|
| Brand name | Viagra® | Cialis® |
| When it is usually taken | About 30 to 60 minutes before sex | As needed, or a low daily dose if prescribed |
| How long it may last | Several hours | Up to about 36 hours |
| Effect of food | A heavy, high-fat meal may slow it down | Less affected by food |
These are general patterns from prescribing information. How each medicine works for you may differ, and results vary.
Which might suit different needs
Because of their timing, some people find one option fits their routine better than the other. For example:
- Sildenafil may suit people who prefer to take a pill shortly before planned sexual activity.
- Tadalafil's longer window may suit people who want more flexibility in timing.
- A low daily dose of tadalafil, if prescribed, may suit people who prefer not to plan around a pill. It is also prescribed for some men with symptoms of an enlarged prostate.
None of these points make one medicine better than the other for everyone. Your health history, other medications and preferences all matter. A clinician may also adjust your dose or suggest switching if one option is not working well or causes side effects.
Side effects to know
Both medicines share many of the same possible side effects. Common ones include:
- Headache
- Facial flushing
- Stuffy or runny nose
- Indigestion
- Dizziness
Tadalafil may also cause back pain or muscle aches. Sildenafil may cause temporary changes in vision, such as a blue tint or sensitivity to light.
Rare but serious side effects can happen. Stop taking the medicine and get medical help right away if you have sudden vision loss, sudden hearing loss, chest pain, or fainting.
Never take sildenafil or tadalafil with nitrates, such as nitroglycerin for chest pain, or with recreational "poppers." The combination can cause a dangerous drop in blood pressure. If an erection lasts more than 4 hours, seek emergency medical care.
Who should talk to a clinician first
A health review matters before taking any ED medication. Be sure to tell your clinician if you:
- Have heart disease or have been told sexual activity is not safe for you
- Have very low or very high blood pressure
- Take nitrates, alpha-blockers or other blood pressure medicines
- Have liver or kidney problems
- Have had a stroke or heart attack
- Have a condition that affects the shape of the penis or a blood condition such as sickle cell disease
ED can sometimes be an early sign of other health issues, such as heart disease or diabetes. A clinician may suggest checking for these as part of your care.
The bottom line
Sildenafil and tadalafil are both widely prescribed PDE5 inhibitors that may help with ED. The main differences are timing, how long they may last and how they fit your routine. Neither is right for everyone, and they must never be combined with nitrates. A licensed clinician can review your health and decide which option, if any, is appropriate.
To see how online ED services work, visit our ED treatment comparison. You can also read how we rank providers and our medical disclaimer.
