Cialis 20 mg: Uses, Benefits, Side Effects and More

You might have seen Cialis® — the popular erectile dysfunction (ED) medication — available in doses ranging from 2.5 mg to 20 mg. Surely, more is better, right?

Well, not always. Cialis 20 mg is an effective erectile dysfunction treatment, but so are the lower doses of the drug.

Below, we’ll cover what Cialis 20 mg is used for, the benefits and side effects of this dose of Cialis, and how it compares to other strengths.

Cialis is a brand name for tadalafil, a widely prescribed ED medication. Tadalafil is a phosphodiesterase type 5 inhibitor or, if you want less of a mouthful, a PDE5 inhibitor.

Cialis is FDA-approved to treat:

• Erectile dysfunction

• Benign prostatic hyperplasia (BPH) or an enlarged prostate

Other forms of tadalafil are used to treat pulmonary arterial hypertension, a type of high blood pressure in the lungs, but Cialis is not prescribed for this condition.

Cialis doses include 2.5 mg, 5 mg, 10 mg, and 20 mg.

You can take Cialis on an as-needed basis and pop a pill before sex, or you can take a daily dose of Cialis so you’re always ready for action.

If you’re taking it as needed, you’ll likely be prescribed 5 mg, 10 mg, or 20 mg. The 10 mg strength is the typical starting dose, and it can be adjusted up or down depending on efficacy and side effects.

But you won’t be taking 20 mg of Cialis daily. The lower doses of 2.5 mg and 5 mg are the daily doses of Cialis.

For ED — which is when you struggle to get or keep an erection — Cialis works by dilating the blood vessels in the penis, which leads to a firmer erection.

Cialis — 20 mg or otherwise — doesn’t just give you an erection, though. Some form of sexual stimulation is required to get hard.

Cialis 20 mg may be a more effective treatment for ED than the 10 mg version. Clinical trials found that 68 to 77 percent of men taking 10 mg Cialis were able to have penetrative sex with their partner. Of those taking 20 mg Cialis, 76 to 85 percent were able to have penetrative sex.

But not all research agrees — a smaller daily dose may be just as effective as the as-needed Cialis treatment.

A systematic review and meta-analysis examined six randomized controlled trials involving more than 1,500 people and compared an as-needed tadalafil treatment to a once-a-day dose. The results showed that both treatments were about equally effective.

Cialis’ benefits include:

• Cialis lasts a long time. While Cialis works similarly to Viagra®, Cialis lasts longer in your body. In fact, Cialis is known as the “weekend pill” for its long half-life. Because you can pop one pill and have sex whenever you like over the next 36 hours (give or take a few hours), it offers more spontaneity. In comparison, avanafil only lasts up to six hours, and Viagra only lasts up to four hours.

• Cialis is effective. Clinical trials show that Cialis is effective for various severities and types of ED, including difficult-to-treat ED. If you find Cialis 10 mg isn’t working, a 20 mg tablet might do the trick.

• You don’t need to take it every day. Depending on your preference and lifestyle, you may not want to take Cialis day in and day out. In fact, the 20 mg dose of Cialis should only be taken as needed.

• Side effects are typically mild. Side effects of Cialis are usually mild and should go away on their own — although they may be worse with higher doses. For example, in clinical trials, 11 percent of people taking tadalafil 10 mg got a headache, whereas 15 percent of those taking tadalafil 20 mg got a headache. Some side effects have the same likelihood in both doses, such as flushing and limb pain. If the side effects of Cialis 20 mg are too much, a healthcare provider may reduce your dose.

• Less flushing. If this is a particularly annoying side effect of other ED medications, switching to Cialis may be the answer. A 2017 systematic review and meta-analysis compared sildenafil (the generic of Viagra) and tadalafil. It found that tadalafil caused lower rates of flushing. Muscle aches and back pain were more common in tadalafil than sildenafil, though. Overall, tadalafil and sildenafil had similar efficacy and safety, but men and their partners preferred tadalafil. You can learn more about the two ED treatments in our Cialis vs. Viagra guide.

As with any medication, Cialis comes with possible side effects.

Common Side Effects

The most common Cialis side effects include:

• Headache

• Dyspepsia (indigestion)

• Back pain

• Myalgia (muscle aches and pain)

• Nasal congestion

• Flushing

• Limb pain

Clinical trials show that most side effects are dose-dependent, meaning you’re more likely to get them with higher doses — and remember, Cialis 20 mg is the highest dose of the drug.

Allergic Reactions

Allergic reactions to Cialis aren’t common but they’re possible. In this case, you may experience:

• Rash

• Hives

• Swelling of the lips, tongue, or throat

• Difficulty breathing or swallowing

Rare Side Effects

There’s also a risk of priapism or prolonged erections — we’re talking for several hours here. It may sound great if you’re suffering from ED, but prolonged erections can be painful and cause irreversible damage to the penis.

If your erection lasts more than four hours, seek medical advice.

You may be more likely to get prolonged, painful erections from Cialis if you have:

• Sickle cell anemia

• Multiple myeloma

• Leukemia

• Anatomic deformations in the penis (like Peyronie’s disease)

There’s also a small risk of vision loss. If you notice any vision loss in one or both eyes, stop taking Cialis and seek medical help. This could be a sign of non-arteritic anterior ischemic optic neuropathy (NAION), which is caused by a lack of blood flow to the optic nerve.

Another serious side effect includes a sudden decrease in hearing or hearing loss. Again, get medical advice as soon as you notice this.

Drug Interactions

There are also a few drug interactions you should know about.

You shouldn’t take Cialis 20 mg (or any dose of the drug) at all if you’re taking nitrates. The combo can cause your blood pressure to drop suddenly, resulting in dizziness, loss of consciousness, or even a heart attack or stroke. Nitrates can be found in medications like isosorbide dinitrate or isosorbide mononitrate, which are used to treat prevent angina caused by heart disease.

Also, watch out for recreational drugs that contain nitrates, like “poppers.”

You also shouldn’t take Cialis if you take medications called guanylate cyclase stimulators, such as riociguat, which treats pulmonary hypertension.

If you’re taking alpha-blockers (like doxazosin, tamsulosin, or alfuzosin) — which mainly treat high blood pressure or BPH — or CYP3A4 inhibitors (like the antibiotic erythromycin and the antifungal medication ketoconazole), which treat a wide variety of conditions, you may be prescribed a low dose of Cialis—probably not the 20 mg kind.

It’s unclear whether it’s safe to take Cialis 20 mg or any dose of the drug with other PDE5 inhibitors, such as:

• Stendra® (avanafil)

• Vardenafil

• Viagra (sildenafil)

Tell your prescribing healthcare provider about the medications or supplements you’re taking before trying Cialis.

Beyond medications, watch out for how much you drink when you’re taking Cialis.

If you have five or more alcoholic drinks, you may experience:

• Increased heart rate

• Decreased standing blood pressure

• Dizziness

• Headache

And a weird one to watch out for: grapefruit and Cialis. A 2020 study on rats found that grapefruit juice inhibits tadalafil metabolism — remember, that’s the active ingredient in Cialis. This can lead to you having more tadalafil in your system, which can increase your risk of side effects.

You can learn more about what to avoid in our guide to tadalafil interactions.

Finally, tell a healthcare provider about any medical conditions you have before taking Cialis so they can determine whether it’s safe for you.

This includes if you have:

• Heart problems like angina (chest pain caused by reduced blood flow to the heart), heart disease, or irregular heartbeats

• Low blood pressure

• Stomach ulcers

• Retinitis pigmentosa (a genetic eye disease)

Cialis is available in a range of doses. Here’s what they’re usually prescribed for:

• Cialis 2.5 mg: If you’re taking Cialis daily, you might be prescribed a 2.5 mg dose. If 2.5 mg isn’t effective and you don’t have any bothersome side effects, the dose may be increased to 5 mg.

• Cialis 5mg: You may be prescribed a 5 mg daily dose of Cialis for BPH. If you have both BPH and ED (the two conditions are linked), you may also get a 5 mg daily dose of Cialis.

• Cialis 10 mg: For an as-needed ED treatment, you’ll most likely be prescribed a 10 mg dose of Cialis to get started. A healthcare provider may then increase your dose to 20 mg or decrease it to 5 mg depending on how you react to the medication and how well it works for you.

• Cialis 20 mg: The big daddy. You’ll most likely only be prescribed Cialis 20 mg as an as-needed ED treatment if you’ve got on well with a 10 mg dose but found that it wasn’t working well enough for you.

There are upsides and downsides to each tadalafil dosage, whether you're taking 20 mg tadalafil or a lower dose.

Daily vs. as-Needed Cialis Tablets

The benefits of Cialis daily include increased spontaneity and less planning around sex. But the downside is you’ll need to remember to take the medication every day, and you may experience more persistent side effects. Check out our guide to daily-use Cialis to learn more.

The benefit of a higher-dose as-needed treatment like Cialis 20 mg is you don’t have to take the medication every day, so you don’t have to worry about missed doses. But the higher your dose, the more likely it is you’ll experience side effects.

A healthcare provider can recommend the best Cialis dosage for you.

FYI: You can’t buy Cialis over the counter. You’ll need to talk with a healthcare professional and get the ED medication prescribed (if you’re deemed eligible for treatment). Remember that brand-name Cialis will typically cost more than tadalafil, even though the medications are the same. Find out more about Cialis pricing.

As tempting as they can be, steer clear of non-prescription Cialis substitutes. They’re not approved by the FDA, and some fake PDE5 inhibitors have been found to contain contaminants. They’ve also been found to contain anywhere from zero to more than 200 percent of the labeled dose of active ingredients, the latter of which could cause serious health problems.

Just one glance at the FDA’s database of tainted sexual enhancement products will show you that many contain hidden ingredients.

If you’re taking Cialis 20 mg before sexual activity, take your prescribed dose at least 30 minutes to two hours before you plan on getting it on. You don’t need to take Cialis with food.

Only take Cialis once per day, max. If you plan on having sex more than once — *fist bump* — Cialis has you covered. It’s been shown to improve erectile function for up to 36 hours.

You can learn more about how long Cialis lasts in our guide.

If you’re taking daily Cialis, whether for ED or BPH, take your dose at roughly the same time every day. You don’t need to worry about when you’ll be having sex.

A healthcare provider will help you determine the best way to take Cialis for your needs.

Cialis 20 mg is a treatment option for ED. It might be right for you if you tolerate the 10 mg tablets but aren’t getting the results you want from the medication.

A healthcare provider can tell you if Cialis 20 mg suits you.

Here's the lowdown:

• Cialis 20 mg is an as-needed ED treatment. You’ll take it at least 30 minutes before having sex. It should provide ED relief for up to 36 hours, allowing you to have sex on your schedule.

• Side effects are mild. You might get a headache, indigestion, or backache. Not ideal when you’re trying to have some sexy time, but these side effects should be mild. Speak to a healthcare provider if any side effects bother you. They may recommend a lower Cialis dose.

• Other ED treatments are available. Cialis 20 mg isn’t your only option. There’s Viagra or sildenafil, Stendra, and Hims Hard Mints, which can contain the active ingredients in Cialis and Viagra in personalized dosages.

You’ll need a prescription for Cialis 20 mg — or any other PDE5 inhibitor. That doesn’t necessarily mean you have to leave the house, though.

Get advice from a licensed healthcare professional today to find out which erectile dysfunction treatments are right for you.