Cialis (tadalafil) is a prescription oral tablet that’s used for certain conditions, including erectile dysfunction. It can interact with other medications and some supplements. For example, Cialis can interact with the drugs amlodipine and Viagra.
Cialis is approved for adult males* to treat:
- erectile dysfunction (ED)
- symptoms of enlarged prostate
- ED and symptoms of enlarged prostate, together
An interaction can occur because one substance causes another substance to have a different effect than expected. Interactions can also occur if you have certain health conditions.
Keep reading to learn about Cialis’s possible interactions. And for more information about Cialis, including details about its uses, see this article.
* In this article, we use the term “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.
Certain health conditions or other factors could raise your risk of harm if you take Cialis. In such cases, your doctor may not prescribe Cialis for you. These are known as contraindications. The list below includes contraindications of Cialis.
If you take a nitrate. If you take a nitrate drug, your doctor likely won’t prescribe Cialis. Nitrates are used to treat a type of chest pain called angina.
Taking Cialis with nitrates may cause very low blood pressure. And having very low blood pressure can lead to dizziness and fainting. In severe cases, very low blood pressure may lead to stroke or heart attack.
Below are examples of nitrates that can interact with Cialis:
- isosorbide mononitrate (Monoket)
- isosorbide dinitrate (Isordil)
- nitroglycerin (Nitro-Dur, NitroMist, Nitrostat)
Certain drugs called poppers are also nitrates. Amyl nitrate is an example of a popper. If you take poppers, your doctor likely won’t prescribe Cialis.
Before taking Cialis, tell your doctor if you’re already taking a nitrate drug. They can recommend treatments other than Cialis for your condition.
If you take a guanylate cyclase stimulator. If you take a guanylate cyclase (GC) stimulator, your doctor likely won’t prescribe Cialis. GC stimulators are used to treat pulmonary arterial hypertension. (This is a form of high blood pressure that occurs in the arteries of your lungs.)
Adempas (riociguat) and Verquvo (vericiguat) are examples of GC stimulators that can interact with Cialis.
Before taking Cialis, tell your doctor if you’re already taking a GC stimulator. They can recommend other treatments other than Cialis for your condition.
If you’ve had an allergic reaction. If you have had an allergic reaction to Cialis or any of its ingredients, your doctor likely won’t prescribe Cialis. This is because taking the drug could cause another allergic reaction. You can ask them about other treatments that may be better options for you.
Before you start taking Cialis, talk with your doctor if any of the factors above apply to you. Your doctor can determine whether Cialis is safe for you to take.
Your doctor will likely recommend limiting the amount of alcohol you drink, if any, during Cialis treatment. This is because both Cialis and alcohol can lower your blood pressure. So, drinking alcohol while taking Cialis could lower your blood pressure even further.
If you drink alcohol, talk with your doctor before starting Cialis treatment. They can tell you whether there’s an amount that’s safe to consume while taking Cialis.
Before you start taking Cialis, tell your doctor and pharmacist about any prescription, over-the-counter, or other drugs you take. Sharing this information with them may help prevent possible interactions.
If you have questions about drug interactions that may affect you, talk with your doctor or pharmacist.
The chart below lists drugs that may interact with Cialis. Keep in mind that this chart does not include all drugs that may interact with Cialis. For more information about some of these interactions, see the “Drug interactions explained” section below.
| Drug group or drug name | Drug examples | What can happen |
| nitrates* | • isosorbide mononitrate (Monoket) • isosorbide dinitrate (Isordil) • nitroglycerin (Nitro-Dur, NitroMist, Nitrostat) | can increase the effect of nitrates |
| guanylate cyclase (GC) stimulators* | • riociguat (Adempas) • vericiguat (Verquvo) | can increase the effect of GC stimulators |
| alpha-blockers | • tamsulosin (Flomax) • alfuzosin (Uroxatral) • terazosin | can increase the effect of alpha-blockers |
| blood pressure medications | • calcium channel blockers, such as amlodipine (Norliqva, Norvasc) • beta-blockers, such as bisoprolol • angiotensin-converting enzyme inhibitors, such as lisinopril (Zestril) • angiotensin receptor blockers, such as losartan (Cozaar) | can increase the effect of blood pressure drugs |
| PDE5 inhibitors | • sildenafil (Viagra, Revatio) • vardenafil (Staxyn) • avanafil (Stendra) • other forms of tadalafil (Adcirca, Alyq) | can increase the risk of side effects from Cialis |
| certain antibiotics | • rifampin (Rifadin, Rimactane) • clarithromycin • erythromycin (E.E.S., EryPed, Ery-Tab, others) | some can increase the risk of side effects from Cialis, and others can make Cialis less effective |
| certain antifungals | • ketoconazole • itraconazole (Sporanox, Tolsura) • voriconazole (Vfend) | can increase the risk of side effects from Cialis |
| certain protease inhibitors | • ritonavir (Norvir) • darunavir (Prezista) • atazanavir (Reyataz) | can increase the risk of side effects from Cialis |
| Certain seizure drugs | • carbamazepine (Carbatrol, Epitol, Tegretol, others) • phenytoin (Dilantin, Phenytek) • phenobarbital | can make Cialis less effective |
* To learn more about this interaction, see the “When should I avoid Cialis?” section above.
Learn more about certain drug interactions that can occur with Cialis.
Interaction with alpha-blockers
Taking Cialis with alpha-blockers can increase the effect of alpha-blockers. These medications are used to treat high blood pressure and enlarged prostate.
Examples of alpha-blockers include:
- tamsulosin (Flomax)
- alfuzosin (Uroxatral)
- terazosin
What could happen
Both Cialis and alpha-blockers can lower blood pressure. Taking these drugs together can lower your blood pressure too much.
What you can do
Before taking Cialis, tell your doctor about any alpha-blockers you take. They’ll tell you whether it’s safe to take Cialis with these drugs. If you do take them together, your doctor may prescribe a lower dosage of Cialis than usual. (To learn more about the dosage of Cialis, see this article.)
Interaction with blood pressure medications
Taking Cialis with blood pressure drugs, known as antihypertensives, can increase the effect of these medications.
Examples of blood pressure drugs include:
- calcium channel blockers, such as amlodipine (Norliqva, Norvasc)
- beta-blockers, such as bisoprolol
- angiotensin-converting enzyme inhibitors, such as lisinopril (Zestril)
- angiotensin receptor blockers, such as losartan (Cozaar)
What could happen
Both Cialis and blood pressure medications can lower your blood pressure too much. Taking these medications together can lead to very low blood pressure.
What you can do
Before taking Cialis, tell your doctor about any blood pressure medications you take. They may monitor your blood pressure more closely than usual while you’re taking these drugs together.
Interaction with certain antibiotics
Taking Cialis with certain antibiotics can raise your risk of side effects from Cialis. (Antibiotics are used to treat infections caused by bacteria.)
Examples of antibiotics include:
- rifampin (Rifadin, Rimactane)
- clarithromycin
- erythromycin (E.E.S., EryPed, Ery-Tab, others)
What could happen
Certain antibiotics may keep the body from breaking down Cialis as it should. This can increase the amount of Cialis in your body. As a result, you may have a higher risk of side effects from Cialis. Or depending on the antibiotic you take, Cialis may be less effective.
What you can do
Before you take Cialis, tell your doctor about any antibiotics you take. They’ll tell you whether it’s safe to take Cialis with these drugs. If they tell you it’s safe, they may monitor you closely for side effects from Cialis.
Cialis may have other interactions. They could occur with supplements, foods, vaccines, or even lab tests. See below for details. Note that the information below does not include all other possible interactions with Cialis.
Does Cialis interact with food?
Cialis may interact with grapefruit or grapefruit juice. Specifically, grapefruit or grapefruit may keep your body from breaking down Cialis as it should. This may increase the amount of Cialis in your body, which could raise your risk of side effects from the drug.
If you have questions about taking Cialis with certain foods or drinks, talk with your doctor or pharmacist.
Does Cialis interact with supplements?
Before you start taking Cialis, talk with your doctor and pharmacist about any supplements, herbs, and vitamins you take. Sharing this information with them may help you avoid possible interactions.
If you have questions about interactions that may affect you, talk with your doctor or pharmacist.
Cialis interactions with herbs
Cialis may interact with an herb called St. John’s wort. (Some people take St. John’s wort to treat depression and various other conditions.)
St. John’s wort may cause your body to break down Cialis faster than it should. This may decrease the amount of Cialis in your body. And a low level of the drug in your body may make Cialis less effective for treating your condition.
If you take St. John’s wort, be sure to tell your doctor before starting Cialis treatment. They may recommend alternatives to St. John’s wort or Cialis.
Cialis and vitamins
There are currently no reports of Cialis interacting with vitamins. But this doesn’t mean that vitamin interactions won’t be recognized in the future.
For this reason, it’s still important to check with your doctor or pharmacist before taking any of these products while taking Cialis.
Does Cialis interact with vaccines?
There are currently no reports of Cialis interacting with vaccines. If you have questions about getting certain vaccines while taking Cialis, talk with your doctor.
Does Cialis interact with lab tests?
There are currently no reports of Cialis interacting with lab tests. If you have questions about getting specific lab tests while taking Cialis, talk with your doctor.
Does Cialis interact with cannabis or CBD?Cannabis (commonly called marijuana) and cannabis products, such as cannabidiol (CBD), have been specifically reported to interact with Cialis. Using cannabis and cannabis products with Cialis can lead to various effects. For some people, using these products together can increase the risk of side effects with Cialis. For others, using cannabis and cannabis products with Cialis can make Cialis less effective than usual.
Before you start treatment with Cialis, tell your doctor and pharmacist if you use cannabis. By sharing this information with them, you may help prevent possible interactions.
Note: Cannabis is illegal at a federal level but is legal in many states to varying degrees.
Certain medical conditions or other health factors may raise the risk of interactions with Cialis. Before taking Cialis, talk with your doctor about your health history. They’ll determine whether Cialis is right for you.
Health conditions or other factors that might interact with Cialis include:
Kidney or liver problems. If you have a kidney or liver problem, tell your doctor before starting treatment with Cialis. Examples of these problems include kidney failure and liver failure. If you have one of these conditions, your doctor may prescribe a lower dosage of Cialis than usual. (To learn more about the dosage of Cialis, see this article.)
Bleeding problems. If you have a bleeding problem, such as hemophilia, tell your doctor before taking Cialis. Your doctor can tell you whether Cialis is safe to take with your condition.
Eye problems. In rare cases, Cialis can cause serious eye problems, including vision loss. Your risk of eye problems with Cialis may be higher if you already have an eye problem before taking the drug. If you have a problem with your optic nerve or retina, tell your doctor before taking Cialis. They can determine whether it’s safe to take Cialis.
Misshaped penis. If you have a condition that affects the shape of your penis, such as Peyronie’s disease, tell your doctor before taking Cialis. Such conditions can increase your risk of priapism from Cialis. Your doctor can tell you whether it’s safe to take Cialis with your condition.
Peptic ulcers. If you have a peptic ulcer, tell your doctor before taking Cialis. This condition may raise your risk of bleeding with the drug. Your doctor can determine whether it’s safe to take Cialis with your condition.
Blood cell problems or blood cancers. If you have a blood cell problem, such as sickle cell anemia, tell your doctor before taking Cialis. Also, tell them if you have a blood cancer, such as leukemia or multiple myeloma. These conditions could raise your risk of priapism from Cialis. Your doctor can tell you whether Cialis is a safe treatment option for you.
Stroke or heart problems. Doctors typically will not prescribe Cialis if you have had a stroke or have certain heart problems. Examples of heart problems include having a heart attack in the past 90 days or having heart failure in the past 6 months.
Also, taking Cialis is not recommended if you have any of the following conditions:
- chest pain during sex
- untreated high or low blood pressure
- untreated abnormal heart rhythm
It is unknown whether Cialis is safe for people who have any of these conditions. If you have any conditions mentioned above, your doctor will likely prescribe a treatment other than Cialis.
- Pregnancy. It is unknown whether Cialis is safe to use during pregnancy. The drug is only prescribed for use in males.* For more information about Cialis and pregnancy, talk with your doctor.
- Breastfeeding. It is unknown if Cialis is safe to use while breastfeeding. The drug is only used in males.* For more information about Cialis and breastfeeding, talk with your doctor.
- Allergic reaction. If you’ve had an allergic reaction to Cialis or any of its ingredients, your doctor will likely not prescribe Cialis. This is because taking the drug could cause another allergic reaction. You can ask them about other treatments that may be better choices for you.
* In this article, we use the term “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.
Find answers to some frequently asked questions about Cialis and possible interactions.
Should I avoid coffee or other sources of caffeine while taking Cialis?
Not necessarily. Coffee and other sources of caffeine are not known to interact with Cialis. It should be safe to consume coffee and caffeine while taking this drug.
According to
To learn more about taking Cialis with coffee or caffeine, talk with your doctor.
Can I take Cialis with nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen?
Yes, you can take Cialis with NSAIDs. There isn’t a known interaction between these medications.
NSAIDs are typically used to reduce swelling or ease pain. Examples of NSAIDs include:
If you’re interested in treatment options to reduce swelling or ease pain while taking Cialis, talk with your doctor or pharmacist.
Does Cialis interact with finasteride?
No, Cialis isn’t known to interact with finasteride (Proscar, Propecia). Finasteride is a drug used to treat enlarged prostate and balding.
Erectile dysfunction (ED), which Cialis is used to treat, is a possible side effect of finasteride. If you have ED with finasteride, your doctor may prescribe a drug to treat it. This could include Cialis. Talk with your doctor to learn more.
Is it safe to take Cialis with Xanax?
Yes, it should be safe to take Cialis with Xanax (alprazolam). There isn’t a known interaction between these medications.
Xanax may cause certain sexual side effects, including changes in your sex drive. And erectile dysfunction (ED) may result from a low sex drive. So, it’s possible that taking Xanax could lead to ED. If you have ED with Xanax, your doctor may prescribe Cialis to treat this condition.
To learn more about Cialis and Xanax, talk with your doctor or pharmacist.
Taking certain steps can help you avoid interactions with Cialis. Before starting treatment, talk with your doctor and pharmacist. Things to discuss with them include:
- Whether you drink alcohol or use cannabis.
- Other medications you take, as well as any vitamins, supplements, and herbs. Your doctor or pharmacist can help you fill out a
medication list . - What to do if you start taking a new drug during your Cialis treatment.
It’s also important to read Cialis’s
Taking Cialis exactly as prescribed can also help prevent interactions.
If you still have questions about Cialis and its possible interactions, talk with your doctor.
Questions you may want to ask your doctor include:
- Do I have any health conditions or take any medications that could affect my Cialis dosage?
- Do other drugs that treat my condition have similar interactions?
- What should I do if I start a new medication while I’m taking Cialis?
To learn more about Cialis, see these articles:
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Disclaimer: Healthline 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.