Cialis (tadalafil) is a prescription brand-name medication. It’s approved by the Food and Drug Administration (FDA) for use in males* to treat:

Depending on how your doctor prescribes Cialis for you, you may take the medication only as needed. Or, you may take it once per day every day. Either way, if you and your doctor agree that Cialis is effective for you, you’ll likely take the drug long-term.

Here are some fast facts on Cialis:

Like other drugs, Cialis can cause side effects. Read on to learn about potential common side effects of Cialis, as well as mild and serious side effects. For a general overview of Cialis, including details about its uses, see this article.

* Sex and gender exist on spectrums. Use of the term “male” in this article refers to sex assigned at birth.

Cialis can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days or weeks. But if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Cialis in clinical trials:

* To learn more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Cialis use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to the Cialis medication guide.

Mild side effects that have been reported with Cialis include:

  • headache*
  • upset stomach and indigestion
  • back pain*
  • muscle pain
  • stuffy nose or runny nose
  • flushing (temporary warmth, redness, or deepening of skin color)
  • pain in your arms or legs
  • upper respiratory infection
  • cough
  • diarrhea
  • urinary tract infection
  • heartburn*
  • abdominal (belly) pain

These side effects may be temporary, lasting a few days or weeks. But if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you develop a side effect while taking Cialis and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.

Cialis may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to the Cialis medication guide.

If you develop serious side effects while taking Cialis, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • Hearing changes. Symptoms can include:
    • trouble hearing
    • dizziness
    • hearing loss
    • ringing in your ears
  • Priapism (a prolonged, painful erection), which is a medical emergency. Symptoms can include:
    • an erection that lasts longer than 4 hours
    • pain in your penis
  • Heart-related side effects.*
  • Side effects that affect the eyes and vision.*
  • Blood pressure changes, including high blood pressure.*
  • Allergic reaction.*

* For more information about this side effect, see “Side effect specifics” below.

While there’s no way to completely avoid Cialis side effects, here are some tips that can help decrease your risk for side effects:

  • Tell your doctor and pharmacist about all of the medications you take. This includes vitamins, herbs, and supplements. Your doctor and pharmacist can check to see if any of the medications you take could interact with Cialis.
  • Tell your doctor about your complete medical history, including any medical conditions you have. This helps your doctor determine if Cialis is safe for you to take.
  • Avoid or minimize drinking alcohol while taking Cialis. Alcohol use can increase your risk for certain side effects.
  • Take Cialis exactly as your doctor prescribes. You should not change your dosage of Cialis without first talking with your doctor.

For more information on lowering your risk for side effects of Cialis, see the “Side effect specifics” section below.

Cialis may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Can Cialis cause side effects that are long-term? Or do Cialis side effects go away?

Most side effects of Cialis go away on their own with time. But some side effects may be long-term, including the following rare side effects:

  • Priapism, which is an erection that lasts longer than 4 hours and won’t go away. If not treated immediately, this can cause irreversible damage to the penis, including loss of the ability to have an erection. You should get emergency medical care right away if you experience priapism.
  • Sudden decrease in vision or loss of vision. This can affect one or both eyes, and can be permanent.

Talk with your doctor or pharmacist if you have additional questions about how long Cialis side effects can last.

What can be the side effects of taking Cialis daily?

These are just a few of the more common side effects reported by people who took Cialis daily in clinical trials:

For a list of side effects reported by people taking Cialis in clinical trials, including people who took the drug daily, see the “Mild side effects of Cialis” and “Serious side effects of Cialis” sections above. You may also view the drug’s prescribing information.

* For more information about this side effect, see “Side effect specifics” below.

What are the side effects of Cialis vs. Viagra?

Cialis and Viagra can both be prescribed to treat erectile dysfunction (ED). These drugs contain the same active ingredient (tadalafil) and belong to the same medication class (phosphodiesterase 5 [PDE5] inhibitors).* So, these drugs share many of the same side effects.

The table below compares some of the mild side effects of Cialis and Viagra:

Can occur with CialisCan occur with ViagraCan occur with both Cialis and Viagra
• pain in your arms or legs• abnormal vision

• dizziness

• nausea

• rash
back pain

flushing (temporary warmth, redness, or deepening of skin color)

headache

heartburn

• muscle pain

• stuffy nose

Below are some serious side effects that Cialis and Viagra (when taken individually) may cause:

If you have additional questions about how Cialis and Viagra compare, talk with your doctor or pharmacist.

* A medication class is a group of drugs that work in a similar way.
† For more information about this side effect with Cialis use, see “Side effect specifics” below.

Do Cialis side effects vary based on whether I’m taking a high or low dose (2.5 mg, 5 mg, 10 mg, or 20 mg)?

Yes, side effects caused by Cialis can vary depending on the strength you’re taking. But most side effects of the drug don’t differ much based on which dose you take. In general, some side effects may be more likely to occur or may be slightly worse with higher doses of Cialis.

To see full details on how Cialis side effects varied by dose in clinical trials, view the drug’s prescribing information.

What are the side effects of generic Cialis?

The generic version of Cialis is tadalafil. (A generic drug is an exact copy of the active drug in a brand-name medication.)

Side effects of tadalafil are the same as those caused by brand-name Cialis. For more information on side effects caused by Cialis, see these sections above:

  • “More common side effects of Cialis”
  • “Mild side effects of Cialis”
  • “Serious side effects of Cialis”

Learn more about some of the side effects that Cialis may cause.

Blood pressure changes, including high blood pressure

Taking Cialis can cause changes in blood pressure, including high blood pressure.

Blood pressure changes weren’t common in people taking Cialis in clinical trials. Low blood pressure was more likely to occur than high blood pressure, but both are possible. These changes tend to be mild.

Symptoms of blood pressure changes can include:

  • dizziness
  • fainting
  • chest pain
  • headache, in severe cases

If you already have high blood pressure or another heart condition, blood pressure changes while taking Cialis may be serious.

Taking certain medications along with Cialis can increase your risk for blood pressure changes. Drinking alcohol can also make this side effect more likely.

What you can do

Before you start taking Cialis, tell your doctor about any medical conditions you have, especially any heart conditions. You should also tell them about all of the medications you take. They can determine whether Cialis is safe for you based on this information.

It’s very important that you do not take medications called nitrates, including nitroglycerin, while you’re taking Cialis. Nitrates are drugs used to treat heart conditions, such as angina (chest pain). Taking Cialis with a nitrate could cause a dangerous decrease in blood pressure.

It’s unlikely that you’ll be asked to monitor your blood pressure while taking Cialis. But if you have symptoms of low blood pressure, your doctor may have you monitor your blood pressure at home. Your doctor will use these blood pressure readings to make sure that it’s safe for you to keep taking Cialis.

Also, if you drink alcohol, talk with your doctor about how much may be safe for you to have while taking Cialis.

Side effects that affect the eyes and vision

Although rare, taking Cialis can cause side effects that affect the eyes and vision. These side effects weren’t common in clinical trials, though.

Specifically, sudden vision loss in one or both eyes is a rare side effect of Cialis. This is because phosphodiesterase 5 (PDE5) inhibitors, such as Cialis, can cause non-arteritic anterior ischemic optic neuropathy (NAION). With NAION, blood flow to your optic nerve is cut off. Your optic nerve sends information from your eyes to your brain.

Other rare side effects reported in clinical trials of Cialis include:

What you can do

Immediately stop taking Cialis and get emergency medical help if you have sudden loss of vision in one or both eyes.

If you have any eye problems, or if you’ve been told that you have a “crowded” optic disc, make sure your doctor knows this before you start Cialis treatment. People with a crowded optic disc may be at increased risk for NAION.

If you have symptoms of eye side effects other than vision loss, contact your doctor right away. They’ll likely want to see you to evaluate your symptoms.

Heartburn

Cialis can cause heartburn, although this side effect wasn’t common in clinical trials.

Symptoms of heartburn can include:

  • a feeling of burning, heat, or warmth in your chest or throat
  • a bad taste in your mouth

What you can do

Heartburn caused by Cialis may go away on its own after a few hours or days.

But if you have heartburn that doesn’t go away, talk with your doctor. Your doctor may recommend treatment for this side effect. This could include dietary changes, such as avoiding foods that trigger heartburn, or a medication such as calcium carbonate (Tums).

Headache

Headache is a possible side effect of Cialis. This was one of the more common side effects reported by people taking the drug in clinical trials.

Alcohol use with Cialis can increase your risk for headaches while taking Cialis.

Rarely, headache can be a symptom of blood pressure changes. Changes in blood pressure are a rare but potentially serious side effect of Cialis. (See “Blood pressure changes, including high blood pressure” above.)

What you can do

In most cases, a headache caused by Cialis should go away on its own after a few hours or days.

If you have headaches while taking Cialis, talk with your doctor about treatments that might be safe for you. Depending on other medical conditions you may have, your doctor may recommend an over-the-counter painkiller. Examples include acetaminophen (Tylenol) and ibuprofen (Advil, Motrin).

Also, if you drink alcohol, talk with your doctor about how much may be safe for you to have while taking Cialis.

If you have headaches that don’t go away, contact your doctor. Although rare, this could be a symptom of blood pressure changes, including high or low blood pressure. Your doctor may want to see you to further evaluate your symptoms.

Heart-related side effects

Taking Cialis can cause some heart-related side effects. These were rarely reported by people taking the medication in clinical trials. Although they’re rare, these side effects can be serious.

Heart-related side effects reported by people taking Cialis in clinical trials include:

  • chest pain
  • heart attack
  • heart palpitations (feeling like your heart skips a beat)
  • fainting after standing up
  • fast heart rate

Cialis can also cause changes in blood pressure, which are discussed above in “Blood pressure changes, including high blood pressure.”

What you can do

Before you start taking Cialis, tell your doctor about any medical conditions you have, especially any heart conditions. You should also tell them about any medications you take. This helps them make sure that Cialis is safe for you to take.

You shouldn’t take Cialis if you have any of the following heart conditions:

Sexual activity can cause strain on your heart. Having sex when your heart isn’t healthy enough can lead to symptoms such as chest pain. People whose hearts aren’t healthy enough for sex should not take Cialis. Your doctor can tell you more about your heart health and taking Cialis.

It is very important that you do not take medications called nitrates, including nitroglycerin, while you’re taking Cialis. Nitrates are drugs used to treat heart conditions, such as angina (chest pain). Taking Cialis with a nitrate could cause a dangerous decrease in blood pressure.

Back pain

Taking Cialis can cause back pain. This was one of the more common side effects reported by people taking the medication in clinical trials.

For most people, back pain caused by Cialis went away on its own within 12 to 48 hours. Most people’s back pain was mild or moderate and was helped by over-the-counter painkillers. But there were rare instances of severe back pain. And in a few cases people stopped taking Cialis due to back pain that didn’t go away.

In general, back pain caused by Cialis most commonly affects the lower back, and sometimes spreads down to the glutes and thighs. In people in clinical trials, lying down or being in a horizontal body position seemed to make the pain worse.

What you can do

In most cases, back pain caused by Cialis should go away on its own after a few hours or days.

If you have back pain with Cialis, talk with your doctor about treatments you can safely take. Depending on other medical conditions you may have, your doctor may recommend an over-the-counter painkiller. Examples of these drugs include acetaminophen (Tylenol) and ibuprofen (Advil, Motrin).

Allergic reaction

As with most drugs, Cialis can cause an allergic reaction in some people.

Symptoms can be mild or serious and can include:

  • rash
  • itching
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically in your lips, eyelids, feet, or hands
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

Note: Flushing by itself can be a mild side effect of Cialis. But if flushing occurs with any of these other symptoms of allergic reaction, you should contact your doctor right away.

What you can do

For mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep taking Cialis. But if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Be sure to talk with your doctor about your health history before you take Cialis. This drug may not be the right treatment for you if you have certain medical conditions or other factors that affect your health. The conditions and factors to consider include:

Blood pressure problems and heart problems. Taking Cialis may cause changes in blood pressure, including high or low blood pressure. And, sexual activity can cause strain on your heart. Due to these risks, it’s very important to tell your doctor about any blood pressure or heart problems you have. Your doctor can determine if your heart is healthy enough for sexual activity, and whether it’s safe for you to take Cialis.

Pulmonary hypertension. Some drugs used to treat pulmonary hypertension should not be used with Cialis, because this combination can cause a dangerous decrease in blood pressure. Be sure to tell your doctor if you have pulmonary hypertension, and whether you take any medications to treat it. Your doctor can determine whether it’s safe for you to take Cialis.

Stroke. Taking Cialis can increase your risk for stroke. You should not use Cialis if you’ve had a stroke within the past 6 months. Make sure to tell your doctor if you have a history of stroke before you take Cialis.

Kidney problems or liver problems. If you have problems with your kidneys or liver, your body may not be able to break down Cialis as quickly as usual. This means the medication can build up in your body, which can increase your risk for side effects. Tell your doctor about any kidney or liver problems you have before you take Cialis. They may start you on a lower Cialis dose than usual.

Retinitis pigmentosa. Retinitis pigmentosa is a rare genetic eye condition that causes vision loss. Cialis can rarely cause vision loss as a side effect. Because of this, you shouldn’t use Cialis if you have retinitis pigmentosa. Your doctor may be able to recommend other treatments for your condition.

Blood cell problems. People with blood cell problems may be at higher risk for priapism (a prolonged, painful erection) with Cialis. These problems include sickle cell anemia, as well as blood cancers, such as leukemia or multiple myeloma. Your doctor may prescribe a lower than usual dose of Cialis for you if you have a condition that affects your blood cells.

Allergic reaction. You shouldn’t take Cialis If you’ve ever had an allergic reaction to Cialis or any of its ingredients. Talk with your doctor or pharmacist about which other treatments are better choices for you.

Alcohol use with Cialis

You should avoid or minimize alcohol use while taking Cialis. This is because alcohol can lower your blood pressure. Cialis can also cause blood pressure changes, including low blood pressure. So the combination of Cialis and alcohol could make this side effect worse, and potentially dangerous.

If you drink alcohol, talk with your doctor about how much is safe for you to have before you start taking Cialis.

Pregnancy and breastfeeding while taking Cialis

Cialis isn’t approved for use in females.* It’s not known whether the drug is safe to use while pregnant or breastfeeding.

If you have questions about Cialis and pregnancy or breastfeeding, talk with your doctor.

* Sex and gender exist on spectrums. Use of the term “female” in this article refers to sex assigned at birth.

Side effects from Cialis can occur, including mild and serious side effects. Some mild side effects of the drug go away with time and don’t require medical attention. But if you have symptoms of serious side effects, you should contact your doctor.

If you’d like to learn more about Cialis, talk with your doctor or pharmacist. They can help answer any questions you have about side effects from taking the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

  • More information on Cialis. For details on other aspects of Cialis, refer to this article.
  • Drug comparison. To learn how Cialis compares with other drugs for erectile dysfunction (ED), read this article.
  • A look at ED. For details on ED, see the Medical News Today men’s health hub, as well as this list of ED articles.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.