Tadalafil interactions to avoid

Drug interactions | Food interactions | Other interactions | Avoiding interactions | When to see a doctor

Tadalafil (brand names Cialis, Adcirca, and Alyq) is a phosphodiesterase type 5 (PDE5) inhibitor that treats erectile dysfunction (ED), benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension (PAH). Tadalafil is an oral tablet and suspension (brand name Tadliq). When used for erectile dysfunction (ED), tadalafil works to help achieve erections for sexual activity. For BPH, tadalafil helps with urinary symptoms, such as frequent urination or the inability to empty the bladder during urination fully. Lastly, for PAH, tadalafil helps relax blood vessels and lowers the blood pressure in the lungs, which makes it easier for the heart to pump blood to the rest of the body.

Tadalafil interacts with nitrates, alpha-blockers, certain anti-infective medications, and sGC stimulators, among other drug classes. Do not take tadalafil with nitrates, sGC stimulators, and other PDE5 inhibitors without consulting a healthcare professional. Tadalafil also interacts with alcohol and grapefruit.


It’s important to be aware of tadalafil interactions as other drugs and foods can affect tadalafil’s effectiveness and cause or worsen side effects. As a medication that can lead to serious effects, certain drug interactions are very important to avoid with tadalafil.

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Tadalafil drug interactions

There are a variety of prescription drugs that can interact with tadalafil, including nitrates, alpha blockers, certain anti-infective medications, sGC stimulators, and other PDE5 inhibitors.

Nitrates

Nitrates are medications that are a type of vasodilator which means they open up blood vessels and improve blood flow. Nitrates are used for treating or preventing chest pain (also called angina) caused by heart disease. These medications cause relaxation within blood vessels, and this can cause several side effects. Since nitrates have serious side effects, some patients are more sensitive to these medications and do not tolerate them well. Additionally, nitrates have many serious drug interactions with other medications, including PDE5 inhibitors like tadalafil. In fact, people should avoid this combination.

Serious low blood pressure can happen when a nitrate drug is taken with tadalafil, as both of these medications can lower blood pressure. Signs of low blood pressure include dizziness, lightheadedness, confusion, nausea, fainting, headache, blurred vision, and irregular heartbeat. In general, nitrates may be taken 24 hours after the last dose of a short-acting PDE5 inhibitor and 48 hours after the last dose of a long-acting PDE5 inhibitor. People who take nitrate medicine and would like to start a PDE5 inhibitor like tadalafil should be aware of this interaction and can talk with their doctor to determine whether nitrate treatment can be discontinued.

Examples of common nitrates include:

• Isordil Titradose (isosorbide dinitrate)
• Ismo (isosorbide mononitrate)
• Nitro-Bid (nitroglycerin)
• Nitro-Dur (nitroglycerin)
• Nitrolingual (nitroglycerin)
• Nitrostat (nitroglycerin)

Alpha blockers

Alpha blockers are medications used to help manage hypertension (high blood pressure) and BPH. These medications work by opening up blood vessels. When used for treating hypertension, alpha blockers can help lower blood pressure. And when used for treating BPH, alpha blockers can improve symptoms of benign prostatic hyperplasia by helping the urine to flow more freely through the urethra. Since alpha blockers can lower blood pressure, there is an increased risk when taken with other medications that can lower blood pressure.

Serious low blood pressure can happen when an alpha blocker medication is combined with tadalafil. It’s important to be aware of common symptoms of low blood pressure, such as dizziness, lightheadedness, confusion, nausea, fainting, headache, blurred vision, and heart palpitations. People must use caution if taking these medications together. Higher doses of either drug are generally associated with a higher risk of unwanted side effects and greater blood pressure changes. It’s recommended that healthcare providers monitor therapy. 

Providers will also ensure that a person is stable on an alpha blocker before starting a PDE5 inhibitor for ED treatment and start the PDE5 inhibitor at the lowest recommended dose. Additionally, separating the dose administration of these medicines may reduce the risk of adverse effects. If tadalafil is used for BPH, using an alpha blocker is not recommended. Contact the healthcare provider for further guidance if there are signs of this possible drug interaction.

Examples of common alpha blockers include:

• Cardura (doxazosin)
• Flomax (tamsulosin)
• Minipress (prazosin)
• Rapaflo (silodosin)
• Terazosin
• Uroxatral (alfuzosin)

Certain anti-infective medications

Anti-infective prescription medicines help prevent or treat infections such as bacterial, fungal, or viral infections. Many anti-infective medications have drug interactions, as some can block enzymes that are important for drug removal from the body or compete for proteins that help clear drugs. These drug interactions can affect the amount of drugs in the body, like tadalafil. Types of anti-infective medications include certain HIV protease inhibitors, azole antifungals, and macrolide antibiotics.

The interaction between certain anti-infective medications that are CYP3A4 inhibitors (block the enzyme CYP3A4 needed for certain drug metabolism) and tadalafil can cause increased amounts of tadalafil in the body. Higher amounts of tadalafil are associated with an increase in adverse effects. Increased side effects of tadalafil include low blood pressure, a prolonged erection of the penis, dizziness, headache, flushing, indigestion, muscle pain, nausea, and fainting.

In general, healthcare providers will need to make changes when combining tadalafil with certain anti-infective medications, and managing this interaction varies according to what tadalafil is being used to treat. Anti-infective medications that inhibit CYP3A4 should not be used, with tadalafil being used for PAH. For people taking tadalafil for ED or BPH each day, the daily dose should be limited to the lower dose of 2.5 mg. For people taking tadalafil as needed, the max dose should be 10 mg and not exceed one dose every 72 hours. It’s best to contact the doctor’s office if there are concerns about this drug interaction.

Examples of certain anti-infective medications include:

• Clarithromycin
• Ery-Tab (erythromycin)
• Ketoconazole
• Noxafil (posaconazole)
• Prezista (darunavir)
• Reyataz (atazanavir)
• Sporanox (itraconazole)
• Vfend (voriconazole)
• Viracept (nelfinavir)

sGC stimulators

Soluble guanylate cyclase (sGC) stimulators are prescription medications that can help relax the heart and blood vessels. These medications include Adempas (riociguat), used to treat pulmonary arterial hypertension (PAH), and Verquvo (vericiguat), which treats heart failure with reduced ejection fraction. A common side effect of sGC stimulators is low blood pressure. When taken with other medications that can lower blood pressure, like tadalafil, serious drug interactions can happen. In fact, people should avoid taking sGC stimulators with tadalafil.

Serious low blood pressure can happen when sGC stimulators are taken with tadalafil since each of these medications can lower blood pressure. Possible symptoms of low blood pressure include confusion, dizziness, lightheadedness, fainting, nausea, headache, blurred vision, and heart palpitations. Healthcare providers will instruct patients not to take riociguat within 24 hours prior to or 48 hours after tadalafil. People who take sGC stimulators who would like to start a PDE5 inhibitor like tadalafil should be cautioned of this interaction and discuss it with their doctor to determine a treatment plan, as these medications should not be taken together.

Examples of sGC stimulators include:

• Adempas (riociguat)
• Verquvo (vericiguat)

Other PDE5 inhibitors

Tadalafil is a PDE5 inhibitor and should not be taken with other PDE5 inhibitors such as Levitra (vardenafil), Stendra (avanafil), and Viagra (sildenafil). As with similar drugs, combining PDE5 inhibitors can increase the risk of side effects that can become serious. Possible side effects that can be increased include hypotension (low blood pressure), dizziness, fainting, headache, flushing, indigestion, muscle pain, nausea, and priapism. This is important to keep in mind as this group of medications has a few possible uses, such as erectile dysfunction (ED), benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension (PAH), and should not be overlapped. Since people should avoid this combination, it’s important to discuss treatment options with the healthcare provider when treating more than one of the conditions tadalafil can treat.

Examples of other PDE5 inhibitors include:

• Levitra (vardenafil)
• Liqrev (sildenafil)
• Revatio (sildenafil)
• Stendra (avanafil)
• Viagra (sildenafil)

Tadalafil food interactions

In addition to interactions with medications, there are other types of tadalafil interactions. Tadalafil has a food interaction with grapefruit and grapefruit juice.

Tadalafil and grapefruit

Grapefruit juice and grapefruit can affect how certain medicines work and should be used cautiously when taking tadalafil. This interaction may cause increases in the amount of tadalafil in the body as grapefruit can block the enzymes used for drug breakdown of tadalafil. It’s important to pay attention to any increases in tadalafil side effects such as headache, indigestion, muscle pain (myalgia), flushing, priapism, and low blood pressure. Discuss with a healthcare provider about grapefruit use and contact the provider if there are concerns about a drug interaction.

Other tadalafil interactions

It’s important to be aware of other tadalafil interactions, including alcohol.


Tadalafil and alcohol 

Alcohol can increase the low blood pressure effects of tadalafil. People should use caution when consuming alcoholic beverages with tadalafil, especially when consuming larger quantities, such as more than three to five drinks. This interaction can increase the risk of dizziness, low blood pressure, increased heart rate, and headache. It’s important to limit any alcohol use to smaller quantities and avoid the combination if possible.

How to minimize tadalafil interactions

Action can be taken to help minimize tadalafil interactions. Healthcare providers should be regularly updated on all health conditions and provided with current medication lists, including prescription drugs, over-the-counter (OTC) medications, herbal products, vitamins, supplements, and recreational drugs. Dangerous drug interactions can happen with nonprescription products like OTC meds and supplements. A pharmacist can be a great resource and can provide medical advice and additional drug information when visiting the pharmacy.

Certain medical conditions can help determine if a drug will be safe or not for a person. Tadalafil should be used with caution in people with kidney disease or liver disease and will sometimes need dose adjustments. Other medical conditions that require caution include anatomical penis deformation, bleeding disorders, cardiovascular disease or heart problems, hereditary degenerative retinal disorders, peptic ulcer disease (PUD), and pulmonary veno-occlusive disease (PVOD). Vision problems can happen with PDE5 inhibitors, including sudden decreases in vision and vision loss in one or both eyes. Seek medical attention in the event of a sudden loss of vision in one or both eyes. People with a history of allergic reactions to tadalafil should avoid the use of the drug.

When to talk to a healthcare provider about tadalafil interactions

Although there are several serious drug interactions included above, there are many other tadalafil drug interactions that are not included. It’s best to communicate openly with healthcare providers about all medications, supplements, medical history, and medical conditions to ensure proper drug management and monitoring. There are alternative treatment options for erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension that may be more suitable for some people.