9 Tadalafil (Cialis) Interactions You Should Know About
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 and medications like riociguat (Adempas). These combinations should be avoided due to the risk of dangerously low blood pressure. Alpha blockers and blood pressure medications can also interact with tadalafil.
Tadalafil sticks around in your body 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 current medication list for them to review.
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Table of contents
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 get or maintain an erection. Why? Because tadalafil lasts longer than other similar medications. And many men may take tadalafil for benign prostatic hyperplasia (enlarged prostate), too.
However, high blood pressure and heart disease are also more common as men get older. And medications used to treat them can interact with tadalafil. Some interactions can have dangerous effects and should be avoided altogether. Others just require monitoring.
Some people take tadalafil daily, while others only take it as needed. And one dose can stick around in your body for several days. This can result in interactions — even if you didn’t take tadalafil and another medication on the same day.
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Your regular prescriber or a telehealth service, may have prescribed tadalafil for your ED. In any case, it’s important to know about tadalafil interactions. Providing your healthcare team with your current medication list can help manage them in advance.
1. Nitrates
Nitrates are used to treat and prevent angina (chest pain) caused by heart disease. Examples include nitroglycerin (Nitrostat), isosorbide mononitrate (Monoket), and isosorbide dinitrate (Isordil).
Phosphodiesterase 5 (PDE5) inhibitors, like tadalafil, are contraindicated with nitrates. This means the combination should be avoided since it can cause harm. Taking these medications together can result in a severe drop in blood pressure (called hypotension). This can make you feel dizzy and possibly cause you to faint or pass out.
2. Alpha blockers
Alpha blockers are a medication class used to treat high blood pressure. Some are also used to help with urinary symptoms from BPH. Examples include terazosin (Hytrin), tamsulosin, (Flomax), and doxazosin (Cardura). Alpha blockers can cause your blood vessels to widen. This can result in a decrease in your blood pressure.
Tadalafil also causes your blood vessels to widen. So taking an alpha blocker with tadalafil can significantly reduce your blood pressure. This can cause dizziness and fainting in some people. To be safe, your prescriber may have you start with a lower Cialis dose for ED if you’re taking an alpha blocker.
3. Blood pressure medications
It’s common to take a blood pressure medication, such as lisinopril, 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.
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 important to use caution with this combination. Tell your prescriber if you experience symptoms such as dizziness or lightheadedness.
4. sGC stimulators
Riociguat (Adempas) is used to manage pulmonary arterial hypertension (high blood pressure in the lungs). And vericiguat (Veroquvo) is used in certain types of heart failure. Both medications are soluble guanylate cyclase (sGC) stimulators. They work by relaxing blood vessels to improve blood flow.
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.
Like nitrates, these medications should not be taken with tadalafil. That’s because your blood pressure could drop dangerously low with this combination.
5. PDE5 inhibitors like Viagra
As discussed earlier, tadalafil is a PDE5 inhibitor. Other common examples of this class include sildenafil (Viagra, Revatio) and vardenafil (Levitra).
For most people, taking more than one PDE-5 inhibitor may not provide an added benefit. Instead, you may be more likely to experience side effects, like dizziness, headache, and flushing.
Your prescriber may recommend taking two PDE-5 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 are medications used to treat viral infections such as hepatitis C and HIV. Examples include ritonavir (Norvir), darunavir (Prezista), and atazanavir (Reyataz). Sometimes they’re combined with medications to help them work better. One example of this is Paxlovid (nirmatrelvir / ritonavir) for COVID-19.
Ritonavir has been shown to increase the blood levels of tadalafil when taken together. Other protease inhibitors may have a similar interaction. This can increase the risk of side effects like vision changes, low blood pressure, and prolonged erections.
Your prescriber may limit your tadalafil dosage with this combination. This may depend on whether you’re taking tadalafil every day or as needed.
7. Anti-infective medications
Certain anti-infective medications, including antibiotics and antifungals, interact with many medications. Examples of these include erythromycin (Ery-Tab), ketoconazole, and itraconazole (Sporonax).
Similar to protease inhibitors, these medications may increase tadalafil levels in the blood. This may result in dizziness and fainting. Your tadalafil dosage may need to be adjusted if you’re also taking one of these medications.
8. Grapefruit
You’ve probably heard that grapefruit can interact with medications. And 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.
9. 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 (like 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 is safe for you to drink.
The bottom line
Tadalafil (Cialis) can interact with other medications, foods, and beverages. Examples include nitrates, alpha blockers, and alcohol. Grapefruit, blood pressure medications, and Paxlovid (nirmatrelvir / ritonavir) can also interact with tadalafil. Some interactions should be avoided, such as nitrates. Others can be managed with dosage changes and monitoring.
Make sure your prescriber and pharmacist have your current 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. (2023). Tadalafil tablet, film coated [package insert]. DailyMed.
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.
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.
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