Cialis vs. Viagra: Which ED Medication is Better?

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Used by millions of men in the United States alone, Cialis (tadalafil) and Viagra (sildenafil) are two of the most popular drugs for treating erectile dysfunction — and for good reason. They both have similar effects, they both treat erectile dysfunction, and they both help men enjoy better sexual performance. But in the battle of Cialis vs. Viagra, which contender wins out?

The truth is, there are a few key differences between Cialis and Viagra that can make one medication a better choice than the other for you.

Below, we’ve compared Cialis and Viagra on a variety of factors, from the amount of time each drug lasts to the time it takes for them to work, potential side effects and interactions you need to be aware of before using either medication.

How Cialis and Viagra Work

Before we get into the differences between Cialis and Viagra, it’s important to explain how these drugs work.

Cialis contains a substance called tadalafil. Tadalafil is a PDE5 inhibitor that works by increasing blood flow to the soft tissue of your penis. By increasing blood flow, tadalafil makes it easier for you to get and keep an erection when you’re sexually aroused.

Viagra contains a substance called sildenafil. Just like tadalafil, sildenafil is a PDE5 inhibitor that increases blood flow to the soft, erectile tissue of your penis.

Because both drugs work by increasing blood flow, they can also be used to treat conditions like hypertension. If you have a heart condition, or if you use medication for high blood pressure, it’s important to talk to your doctor before using Cialis or Viagra.  

Which Drug Lasts Longer?

The biggest difference between Cialis and Viagra is the amount of time each drug stays active in your body.

Cialis is a long-lasting erectile dysfunction drug. On average, it works for as long as two days after you take it. Because it lasts so long, it’s been dubbed the “weekend pill” by users and the mass media.

This means Cialis is a great choice if you need to make sure you can get an erection but don’t know exactly when you’ll have sex. If you’re going away for a weekend with your partner or just want to be prepared at any time, a single dose of Cialis is usually more than enough.

Viagra, on the other hand, is a shorter-acting erectile dysfunction drug. Most of the time, Viagra lasts for five to six hours, with the effects of the medication usually starting to wear off three to four hours after you take it.

This means Viagra is a great choice if you need a short-acting erectile dysfunction drug to keep you hard and self-confident for one evening. While Cialis is a great choice for weekends, Viagra is a good option if you can predict when you’re about to have sex.

It’s important to remember that Cialis and Viagra don’t always last for exactly 24-36 or five to six hours. Factors such as your bodyweight, eating habits and cardiovascular health can affect how long each medication provides relief from erectile dysfunction.

Verdict: Cialis lasts longer and is better for weekends, whereas Viagra is usually a better choice if you only need to treat ED for one evening.

Which Drug is More Effective?

Cialis and Viagra are both effective as treatments for erectile dysfunction. Clinical trials of both medications show that more than 80 percent of men are able to achieve satisfactory erections at the recommended dose:

  • In a clinical trial of Cialis, 81 percent of men reported that the medication gave them improved erections. 71 percent of men with severe erectile dysfunction reported improved erections from Cialis.

  • In a clinical trial of Viagra, 82 percent of men reported improved erections after taking a 100mg dose of the medication. Viagra was also effective at lower doses, with 62 percent and 74 percent of men reporting improvements at 25mg and 50mg doses, respectively.

In short, Cialis and Viagra are equally effective at treating erectile dysfunction. Both medications produce a noticeable improvement in erection quality at a normal dose, as well as good results at a lower-than-normal dose.

Verdict: Cialis and Viagra both work well for treating ED, with no real difference between the two drugs in terms of erection quality or sexual performance.

Which Drug Works Faster?

Cialis and Viagra both start working quickly after you take them. A normal dose of Cialis usually starts to produce an improvement in your erections after about 30 minutes. It can take up to two hours for Cialis to become fully effective.

Most of the time, Viagra starts working in about 30 minutes. It can take up to one hour for Viagra to become fully effective, meaning you’ll want to take it an hour or more before you plan to have sex for best results.

Verdict: Cialis and Viagra both start to work in 30 minutes but can take upwards of one hour to produce optimal results. Cialis can take up to two hours to reach its full concentration.

Are Viagra and Cialis Affected by Food?

Cialis is not affected by food, meaning it will start working in roughly the same amount of time regardless of whether you take it on an empty or full stomach.

Viagra, on the other hand, can be affected by your food choices. Eating a high-fat meal before taking Viagra can slow down the drug’s absorption, meaning you might not notice the effects of Viagra for more than one hour after taking it.

For best results, you should take Viagra on an empty stomach at least one hour before having sex. If you need to eat before taking Viagra, try to avoid foods with a high fat content, as they’re most likely to slow your body’s absorption of the medication.

Verdict: Because Cialis is unaffected by food, it’s a better option if you need to eat before taking your ED medication.

Cialis Side Effects vs. Viagra Side Effects?

Cialis side effects and Viagra side effects are very similar in nature, because the drugs effect the body in  a lot of the same ways. The most common side effects of both drugs are headaches, nasal congestion, facial flushing, heartburn/indigestion and temporary blurred vision.

Muscle aches are Cialis side effects and Viagra side effects, although these aren’t as common as facial flushing, nasal congestion and other side effects. It’s also possible for the increase in your nitric oxide levels caused by Cialis or Viagra to make you feel slightly dizzy.

Viagra and cialis side effects usually occur while the medications are active. However, it’s also possible for some (particularly headaches and heartburn/indigestion) to occur as the drugs are becoming less active in your body.

Cialis and Viagra can both cause priapism (an erection that lasts for four hours or longer). This is a very rare side effect. If you experience a lasting, persistent erection for four hours or longer after using either drug, seek medication attention as soon as possible.

Because Cialis stays in your body longer than Viagra, you might notice Cialis side effects for longer. If you’re prone to side effects, Viagra’s shorter duration of action can make it a better option.

You can also avoid or lighten many of the side effects of Cialis and Viagra by taking a low dose of the medication. We’ve covered this in more detail below.

Verdict: The side effects of Cialis and Viagra are largely identical. However, since Cialis lasts for longer in your body, you might experience side effects for longer than with Viagra.

Our guide to what you should expect from erectile dysfunction medication goes into more detail on the potential side effects of Cialis and Viagra, as well as their main causes.

Which Drug is the Safest?

Cialis and Viagra are both extremely safe, with studies showing few negative side effects and an excellent safety record overall for both drugs. However, Cialis and Viagra can become unsafe if used with certain other medications:

  • If you use nitrates or other medications to treat hypertension, you should not use Cialis or Viagra. Used together, nitrates and PDE5 inhibitors can cause a drop in your blood pressure that can cause serious health issues.

  • While it’s perfectly safe to have a glass of wine, beer or any other light drink after taking Cialis or Viagra, you should avoid drinking large amounts of alcohol with either drug. The combination of alcohol and a PDE5 inhibitor can lead to orthostatic hypotension.

  • Grapefruit and grapefruit juice can affect the way your body metabolizes tadalafil and sildenafil, the active ingredients in Cialis and Viagra. When you’re using these drugs, you’ll need to avoid any foods that contain grapefruit.

  • If you have any heart condition, you’ll need to inform your doctor before considering Cialis or Viagra.

Overall, Cialis and Viagra are both safe, effective drugs. As with all prescription medicine, you’ll need to talk to a doctor about your symptoms and overall health before using either drug to treat erectile dysfunction.

Verdict: Aside from the four situations listed above, Cialis and Viagra are both safe drugs with few serious side effects.

Cialis and Viagra Dosages

Although Cialis and Viagra have similar effects, the two medications are effective at different dosages. Cialis comes in four different dosages:

  • 10mg. This is the recommended starting dose of Cialis. Your doctor will likely prescribe you Cialis at this dosage if you’ve never taken the medication before. Most younger men with ED experience good results from the 10mg dosage.

  • 20mg. This is the highest available dose of Cialis. If you don’t respond to the 10mg dose or find it doesn’t provide enough of an improvement, you should talk to your doctor about switching to the full 20mg dose.

  • 2.5 and 5mg. These dosages of Cialis are intended for everyday use. Known as “Cialis Daily,” these lower-dose tablets of Cialis are designed for men with ED who would like to have spontaneous sex without having to plan their medication ahead of time.

Viagra comes in three different dosages:

  • 50mg. This is the recommended starting dose of Viagra. Your doctor will likely prescribe Viagra at this dosage if you’re young, have mild to moderate ED and haven’t previously used Viagra or any other ED medications.

  • 100mg. This is the highest available dose of Viagra. This dose is usually prescribed if you don’t notice enough of an improvement from the 50mg tablet.
  • 25mg. This is the smallest available dose of Viagra. Many younger men and men with mild ED notice an improvement from this dose of Viagra. This dose is also less likely to cause side effects such as facial flushing, headache and heartburn/indigestion.

Verdict: Cialis and Viagra are both available at different dosages, making it easy to take just the right amount of either medication for your needs.

Which Drug is Better?

There’s no “best” drug when it comes to treating erectile dysfunction. Cialis and Viagra produce very similar effects, yet each drug has its own advantages:

  • If you need a “weekend” erectile dysfunction drug that lasts for a long time and lets you have sex whenever you’d like without having to plan ahead, you’ll probably prefer Cialis.

  • If you prefer a shorter-acting erectile dysfunction drug that lets you have sex for a single evening without staying in your system too long, you’ll probably prefer Viagra.

Learn More About Erectile Dysfunction Treatments

Looking for a reliable, science-backed treatment for erectile dysfunction? We’ve got you fully covered. Our guide to the most common erectile dysfunction treatments compares the three most common ED medications: Viagra (sildenafil), Cialis (tadalafil) and Levitra (vardenafil).

You can also learn more about how to use erectile dysfunction drugs in our guide to using ED medication effectively, which covers everything from how to eat before using Viagra and other PDE5 inhibitors to potential drug interactions.



This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.