Key takeaways:
Tadalafil (Cialis) is a medication used to treat erectile dysfunction. It’s also used to treat symptoms of benign prostatic hyperplasia.
Tadalafil can interact with nitrates, riociguat (Adempas), and alpha blockers. Blood pressure medications and grapefruit can also interact with tadalafil.
Tadalafil stays in your system for several days after taking it. This can result in an interaction even if you didn’t take it on the same day as another medication.
Your prescriber can determine which tadalafil interactions may affect you and how to manage them. Not all interactions need to be avoided entirely. Be sure to share your medication list for them to review.
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By age 50, as many as 5 out of 10 men experience erectile dysfunction (ED). For some, tadalafil (Cialis) may be a preferred medication to help get or maintain an erection. Why? Because tadalafil lasts longer than other similar medications for ED. And many men may take tadalafil for benign prostatic hyperplasia (BPH; enlarged prostate) too.
At the same time, high blood pressure and heart disease are also more common among older adults. And medications used to treat them can interact with tadalafil. Some interactions can have dangerous effects and should be avoided altogether. Others can be managed with careful monitoring.
Whether you’re taking tadalafil daily or as needed, a single dose can stay in your system for several days. That means interactions may still occur — even if you don’t take tadalafil and another medication on the same day. Here’s what you should know about tadalafil interactions.
Tadalafil (Cialis) interactions at a glance
Regardless of whether you received a tadalafil prescription from your regular prescriber or a telehealth service, be sure to share your medication list. This helps your healthcare team manage potential interactions ahead of time.
This isn’t a full list, but the following medications, foods, and drinks can interact with tadalafil:
Nitrates, such as nitroglycerin (Nitrostat), isosorbide mononitrate (Monoket), and isosorbide dinitrate (Isordil)
Alpha blockers, such as terazosin (Hytrin), tamsulosin (Flomax), and doxazosin (Cardura)
Blood pressure medications, such as lisinopril (Zestril, Qbrelis), losartan (Cozaar, Arbli), and amlodipine (Norvasc)
Soluble guanylate cyclase (sGC) stimulators, such as riociguat (Adempas)
Other phosphodiesterase 5 inhibitors (PDE5 inhibitors), such as sildenafil (Viagra), vardenafil, and avanafil (Stendra)
Protease inhibitors, such as ritonavir (Norvir), darunavir (Prezista), and atazanavir (Reyataz)
Paxlovid (nirmatrelvir / ritonavir)
Anti-infective medications, such as erythromycin (Ery-Tab), ketoconazole, and itraconazole (Sporonax)
Anti-seizure medications, such as carbamazepine (Tegretol), phenytoin (Dilantin), and phenobarbital
St. John’s wort
Rifampin (Rifadin)
Alcohol
Grapefruit
Next, we’ll cover what you should know about 10 of these tadalafil interactions.
1. Nitrates
Nitrates, such as nitroglycerin, are used to treat and prevent angina (chest pain) caused by heart disease. Taking tadalafil with nitrates can result in a severe drop in blood pressure (called hypotension). This can make you feel dizzy and possibly cause you to faint.
Because of this risk, PDE5 inhibitors like tadalafil are contraindicated with nitrates. This means the combination should be avoided since it can cause harm.
2. Alpha blockers
Alpha blockers, such as terazosin and doxazosin, are used to treat high blood pressure. Some, such as tamsulosin, also help with urinary symptoms from BPH. Similar to tadalafil, alpha blockers can cause your blood vessels to widen, resulting in lower blood pressure.
Taking an alpha blocker with tadalafil can significantly reduce your blood pressure. This can cause dizziness and fainting in some people. To manage this risk, your prescriber may have you start with a lower Cialis dose for ED if you’re taking an alpha blocker.
3. Blood pressure medication
It’s common to take a blood pressure medication, such as lisinopril, losartan, or amlodipine, with tadalafil. That’s because having high blood pressure can be a contributing factor for ED. What’s more, some blood pressure medications can also cause ED.
Cialis daily versus as needed: Taking lower Cialis doses daily instead of as needed can be a convenient option for erectile dysfunction. Here are the key differences between Cialis daily versus as needed to consider.
Cialis tips: New to Cialis or just looking to get better results? Here are pharmacist-backed tips for how to take Cialis.
Cialis side effects: Do you get headaches after taking Cialis? Learn more about potential Cialis side effects and how to manage them.
There are several types of medications available to lower your blood pressure if it’s too high. And they all work differently to achieve this effect. Examples include diuretics (water pills), angiotensin-converting enzyme (ACE) inhibitors, and calcium channel blockers. When they’re taken with tadalafil, some people experience a small drop in blood pressure.
This interaction may not cause meaningful blood pressure changes for everyone. But it’s still best to use caution with this combination. Tell your prescriber if you experience side effects such as dizziness or lightheadedness.
4. sGC stimulators
Riociguat is used to manage different types of pulmonary hypertension (high blood pressure in the lungs). And vericiguat (Verquvo) is used in certain types of heart failure. Both medications are sGC stimulators. They work by relaxing blood vessels to improve blood flow.
Similar to nitrates, sGC stimulators should not be taken with tadalafil. That’s because your blood pressure could drop dangerously low with this combination.
5. PDE5 inhibitors like Viagra
Tadalafil is a PDE5 inhibitor. Taking Cialis with Viagra (sildenafil) or other PDE5 inhibitors, such as vardenafil or avanafil, may not provide an added benefit. Instead, you may be more likely to experience side effects such as dizziness, headache, and flushing.
That said, your prescriber may recommend taking two PDE5 inhibitors in certain situations. For example, they may have you take Cialis every day and Viagra as needed. But you should always check with them before taking more than one of these medications at the same time.
6. Protease inhibitors
Protease inhibitors, such as ritonavir, darunavir, and atazanavir, are medications used to treat viral infections such as hepatitis C and HIV. Sometimes they’re combined with medications to help them work better, such as with Paxlovid for COVID-19.
When they’re taken together, ritonavir has been shown to increase blood levels of tadalafil. Other protease inhibitors may have a similar interaction. This can increase the risk of side effects such as vision changes, low blood pressure, and prolonged erections (priapism).
Your prescriber may limit your tadalafil dosage with this combination. Your maximum dosage will depend on whether you’re taking tadalafil every day or as needed.
7. Anti-infective medications
Certain anti-infective medications, such as erythromycin, ketoconazole, and itraconazole, interact with many medications — including tadalafil. These medications can raise tadalafil levels in the blood, increasing the risk of side effects, such as low blood pressure.
If you’ve been prescribed one of these anti-infectives, your healthcare team may need to adjust your tadalafil dosage.
8. Anti-seizure medications
Some anti-seizure medications, including carbamazepine, phenytoin, and phenobarbital, can lower the amount of tadalafil in your body. They speed up how tadalafil is broken down, which may make it less effective.
If you’re taking one of these medications, your healthcare team may recommend a higher tadalafil dose or a different treatment altogether.
9. Grapefruit
You’ve probably heard that grapefruit can interact with medications. Tadalafil — as well as other PDE5 inhibitors — is no exception. For some people, this combination may cause a drop in blood pressure. But this can vary by person.
Is consuming grapefruit or grapefruit juice part of your regular routine? If so, ask your prescriber or pharmacist about how much is safe with your medications.
10. Alcohol
Both tadalafil and alcohol can cause your blood vessels to relax. When you combine the two, this effect can cause your blood pressure to drop. This may be more apparent when changing positions (such as from sitting to standing). You may feel dizzy and be more likely to fall.
Because of this, it’s best to minimize or avoid alcohol while taking tadalafil. And if you’re taking tadalafil for ED, alcohol isn’t going to do you any favors. Talk to your prescriber about how much alcohol (if any) is OK for you to drink.
Frequently asked questions
Adderall and Cialis don’t have a direct interaction. But it’s a good idea to check with your healthcare team before combining them, especially if you have heart or blood pressure issues. This is because Adderall can increase blood pressure and heart rate, while tadalafil can lower blood pressure.
Yes, you can typically drink caffeinated beverages when taking tadalafil. There’s no known direct interaction between the two. But it’s best to discuss this combination with your healthcare team, particularly if you have underlying heart problems or are sensitive to blood pressure changes. They can provide guidance for how much (if any) caffeine is OK to drink with tadalafil.
Several factors can affect how well Cialis works, including:
Heavy alcohol use: Drinking too much alcohol can interfere with Cialis and increase the risk of side effects such as dizziness and low blood pressure.
Certain medications: Medications and supplements that speed up how your body breaks down tadalafil can make your current Cialis dose less effective. Examples of these include certain anti-seizure medications, rifampin, and St. John’s wort.
Decongestants like Sudafed (pseudoephedrine): These can narrow blood vessels and counteract the effects of Cialis, making it harder to get or maintain an erection. In fact, pseudoephedrine is sometimes used to treat erections that last too long.
Health and lifestyle factors: Changes in underlying health conditions, such as diabetes, may affect how well Cialis works. Lifestyle factors such as smoking and foods you eat can also contribute.
Talk to your prescriber if Cialis doesn’t seem to be working for you. They can help determine the cause and best next steps.
Yes, certain herbs and supplements can interact with Cialis. For example, St. John’s wort may make Cialis less effective by speeding up how it’s broken down in the body. Other supplements that lower blood pressure, such as arginine or ginseng, may increase the risk of dizziness. It’s also important to note that some ED supplements contain hidden PDE5 inhibitors (like tadalafil). Always check with your healthcare team before adding a new supplement or herbal product.
Adderall and Cialis don’t have a direct interaction. But it’s a good idea to check with your healthcare team before combining them, especially if you have heart or blood pressure issues. This is because Adderall can increase blood pressure and heart rate, while tadalafil can lower blood pressure.
Yes, you can typically drink caffeinated beverages when taking tadalafil. There’s no known direct interaction between the two. But it’s best to discuss this combination with your healthcare team, particularly if you have underlying heart problems or are sensitive to blood pressure changes. They can provide guidance for how much (if any) caffeine is OK to drink with tadalafil.
Several factors can affect how well Cialis works, including:
Heavy alcohol use: Drinking too much alcohol can interfere with Cialis and increase the risk of side effects such as dizziness and low blood pressure.
Certain medications: Medications and supplements that speed up how your body breaks down tadalafil can make your current Cialis dose less effective. Examples of these include certain anti-seizure medications, rifampin, and St. John’s wort.
Decongestants like Sudafed (pseudoephedrine): These can narrow blood vessels and counteract the effects of Cialis, making it harder to get or maintain an erection. In fact, pseudoephedrine is sometimes used to treat erections that last too long.
Health and lifestyle factors: Changes in underlying health conditions, such as diabetes, may affect how well Cialis works. Lifestyle factors such as smoking and foods you eat can also contribute.
Talk to your prescriber if Cialis doesn’t seem to be working for you. They can help determine the cause and best next steps.
Yes, certain herbs and supplements can interact with Cialis. For example, St. John’s wort may make Cialis less effective by speeding up how it’s broken down in the body. Other supplements that lower blood pressure, such as arginine or ginseng, may increase the risk of dizziness. It’s also important to note that some ED supplements contain hidden PDE5 inhibitors (like tadalafil). Always check with your healthcare team before adding a new supplement or herbal product.
The bottom line
Tadalafil (Cialis) can interact with nitrates, alpha blockers, and riociguat (Adempas). Grapefruit, blood pressure medications, and Paxlovid (nirmatrelvir / ritonavir) can also interact with tadalafil. Some interactions should be avoided, such as nitrates and riociguat. Others, such as blood pressure medications, can often be managed with dosage changes and monitoring.
Make sure your prescriber and pharmacist have your medication list. They can review it to determine which interactions may affect you and how to manage them.
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References
Accord Healthcare. (2024). Tadalafil tablet, film coated [package insert]. DailyMed.
Campbell, N., et al. (2013). Adulteration of purported herbal and natural sexual performance enhancement dietary supplements with synthetic phosphodiesterase type 5 inhibitors. The Journal of Sexual Medicine.
Cui, H., et al. (2014). Efficacy and safety of long-term tadalafil 5 mg once daily combined with sildenafil 50 mg as needed at the early stage of treatment for patients with erectile dysfunction. Andrologia.
Evans, J. D., et al. (2015). A comparison of the available phosphodiesterase-5 inhibitors in the treatment of erectile dysfunction: A focus on avanafil. Patient Preference and Adherence.
Memorial Sloan Kettering Cancer Center. (2021). Priapism (an erection that lasts too long).
Mykoniatis, I., et al. (2021). Assessment of combination therapies vs monotherapy for erectile dysfunction. JAMA Network Open.
Rew, K. T., et al. (2016). Erectile dysfunction. American Family Physician.
