Sildenafil vs. tadalafil: which is better for ED?

When it comes to treating erectile dysfunction (ED), two of the most well-known medications are sildenafil (Viagra) and tadalafil (Cialis). Both are PDE5 inhibitors, a type of medication that boosts blood flow to help you get and maintain an erection. But they differ in how fast they work and how long they last. 

Let’s break down the key differences to help you choose the right fit.

Sildenafil vs. tadalafil: which works faster?

Both sildenafil and tadalafil start working in about 30–60 minutes, but sildenafil’s onset can be delayed by a high-fat meal. 

Sildenafil is usually taken about an hour before sex. However, you can take it anywhere from 30 minutes to four hours beforehand, depending on how your body responds.

Tadalafil also begins working within 30 minutes (as quickly as 20 minutes, for some people) and isn’t affected by food. Its effects can last up to 36 hours, so you have a wider window for sexual activity.

If you’re prescribed daily tadalafil, you don’t need to time your medication based on planned sexual activity. Just take it at the same time each day to maintain steady levels.

Sildenafil vs. tadalafil: which lasts longer?

Tadalafil lasts up to 36 hours — much longer than sildenafil, which works for about 4–6 hours.

Because sildenafil provides a shorter window of effectiveness, it’s typically best for planned sexual activity. You should only take your ED medication as prescribed, no more than once per day.

Tadalafil, on the other hand, stays active for up to 36 hours, so there’s no need to plan your timing as carefully. Its lower doses also come as a daily option, which keeps a steady amount in your system so you can be ready whenever the moment feels right.

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Sildenafil vs. tadalafil: cost comparison 

Generic sildenafil (100 mg) typically costs about $2–$29 for 30 tablets. Generic tadalafil (5 mg) typically costs around $2–$29 for 30 tablets with discounts.

Without insurance or discounts, retail prices can climb quickly — as much as $440 for sildenafil and $261 for tadalafil. That said, savings programs and coupons, such as those available on sites like GoodRx and SingleCare, can make both drugs much more affordable. 

Brand-name Viagra and Cialis are far pricier, often running over $689 and $314, respectively, depending on where you live, even with discounts.

Sildenafil vs. tadalafil: dosage and schedules 

Healthcare providers usually prescribe sildenafil at a starting dose of  50 mg or 100 mg to be taken as-needed about an hour before sex. Tadalafil typically starts at 10–20 mg as needed or 2.5–5 mg daily for ongoing use.

Of course, starting doses may vary depending on factors like your age or other health conditions. Be sure to follow your healthcare provider’s instructions closely. 

You should only take one dose of sildenafil in a 24-hour period, about 30–60 minutes before sexual activity. If you notice side effects, your healthcare provider may adjust your dosage accordingly. 

Tadalafil comes in several forms and strengths: 2.5 mg, 5 mg, 10 mg, and 20 mg tablets. It can be taken as needed or, for the lower doses, daily to maintain steady levels in your system. 

Studies show that sildenafil and tadalafil are generally both safe and effective for treating ED. However, many people prefer tadalafil. That’s because it lasts longer, allows for more spontaneity, and can even boost sexual confidence.

Here’s a quick look at the most common side effects for each.

Sildenafil side effects

Common side effects of sildenafil include:

• Headache

• Facial flushing

• Indigestion

• Nasal congestion

• Dizziness

• Visual changes (such as a blue tint or other color disturbances)

Most sildenafil side effects are mild and short-lived. Still, if you ever have serious symptoms — especially an erection lasting longer than four hours — get medical help right away.

Avoid taking sildenafil if you’re using nitrates (like nitroglycerin for chest pain) or nitrites (“poppers”). This combo can make your blood pressure dangerously low. It also shouldn’t be used with guanylate cyclase stimulators (like riociguat).

These aren’t the only medications that can potentially interact with sildenafil. Before starting sildenafil, talk with your healthcare provider to make sure it’s safe for you, especially if you have heart, circulation, or blood pressure issues.

Tadalafil side effects 

The side effects of tadalafil can be less common or milder than those seen with sildenafil for some people. They also often improve as you adjust to the medication. 

The most common side effects to look out for include:

• Headache

• Indigestion

• Back pain

• Muscle aches

• Nasal congestion

• Facial flushing

Similar to sildenafil, avoid taking this medication if you use nitrates or guanylate cyclase stimulators. You should also skip tadalafil if you’ve had a serious allergic reaction to it or any of its ingredients.

These aren’t the only reasons to avoid tadalafil. Before starting tadalafil, let your healthcare provider know about all medications, supplements, and health conditions you have so they can determine if tadalafil is the right choice for you.

Sildenafil and tadalafil are commonly used to treat erectile dysfunction (ED), among other conditions. They belong to the same drug class and work by increasing blood flow in certain areas of the body.

• Sildenafil (Viagra) works quickly and is best for planned sex. It’s taken as needed about an hour before sexual activity.

• Tadalafil (Cialis) lasts up to 36 hours, making it ideal for more spontaneity. It can be taken as needed or at a lower dosage for daily use.

• Both treat ED, and tadalafil can also help with BPH (enlarged prostate) symptoms when it is taken at a low-level daily dose.

• Some men prefer sildenafil for its shorter window, while others choose tadalafil for its flexibility and longer effect.