Learn which medications, supplements, and foods interact with Tadalafil (Cialis). Includes major and moderate interactions and what to tell your doctor.
Tadalafil (brand name Cialis) is generally safe when used as prescribed, but it can interact with other medications, supplements, and even certain foods. Some of these interactions are life-threatening — particularly with nitrate medications.
This guide covers the major and moderate drug interactions you should know about, what to avoid, and what to tell your doctor before starting Tadalafil.
Tadalafil works by relaxing blood vessels and lowering blood pressure in targeted areas. If you take other medications that also lower blood pressure or affect the same enzyme pathways, the combined effects can be dangerous.
Tadalafil is also metabolized (broken down) in the liver by an enzyme called CYP3A4. Medications that block or speed up CYP3A4 can change how much Tadalafil ends up in your bloodstream — either increasing the risk of side effects or making the drug less effective.
These interactions are serious. In some cases, Tadalafil should never be combined with these medications.
This is the most dangerous interaction. Never take Tadalafil with any form of nitrate medication. The combination can cause a severe, potentially fatal drop in blood pressure.
Common nitrates include:
If you use nitrates for chest pain (angina), you cannot take Tadalafil. Talk to your doctor about alternative ED treatments.
Riociguat is used to treat pulmonary hypertension and chronic thromboembolic pulmonary hypertension. Combining it with Tadalafil can cause a dangerous drop in blood pressure. These two drugs should never be used together.
Alpha-blockers are prescribed for BPH and high blood pressure. When combined with Tadalafil, they can cause additive blood pressure lowering, leading to dizziness, lightheadedness, or fainting.
Common alpha-blockers:
If you take an alpha-blocker, your doctor should start Tadalafil at the lowest dose (2.5 mg daily or 5 mg as-needed) and make sure your blood pressure is stable on the alpha-blocker before adding Tadalafil.
These drugs slow down the breakdown of Tadalafil in your liver, causing higher-than-normal drug levels in your blood. This increases the risk of side effects like headache, flushing, and low blood pressure.
Examples include:
If you take any of these, your doctor should limit Tadalafil to a maximum of 10 mg every 72 hours for as-needed use. Daily dosing should not exceed 2.5 mg.
These drugs speed up the breakdown of Tadalafil, meaning less of the drug stays in your system and it may not work as well.
Examples include:
If you take one of these medications, your doctor may need to adjust your Tadalafil dose or consider an alternative.
Tadalafil has a mild blood-pressure-lowering effect. If you already take antihypertensives — including ACE inhibitors, ARBs, beta-blockers, or calcium channel blockers like Amlodipine (Norvasc) — the combined effect may cause dizziness or lightheadedness, especially when standing up quickly.
This doesn't mean you can't take Tadalafil with blood pressure medication. It just means your doctor should monitor you and may start with a lower dose.
These may increase Tadalafil levels, though less dramatically than strong inhibitors:
Some common supplements and OTC products can interact with Tadalafil:
Always tell your doctor about all supplements you take, including herbal products. "Natural" does not mean interaction-free.
Grapefruit inhibits CYP3A4, the same enzyme that breaks down Tadalafil. Consuming grapefruit or grapefruit juice while taking Tadalafil can increase drug levels in your blood, raising the risk of side effects. It's best to avoid grapefruit entirely while taking Tadalafil.
Alcohol and Tadalafil both lower blood pressure. Drinking alcohol while taking Tadalafil can increase the risk of dizziness, lightheadedness, headache, and flushing. While moderate alcohol use (1–2 drinks) is generally tolerable, heavy drinking should be avoided. Alcohol can also worsen erectile dysfunction independently.
Before your doctor prescribes Tadalafil, make sure they know about:
If you start a new medication while already taking Tadalafil, tell that prescriber about your Tadalafil use as well. Interactions go both ways.
Most people take Tadalafil without problems, but knowing about potential interactions is important for your safety. The biggest danger is combining Tadalafil with nitrates — this is absolutely contraindicated. Other interactions, like those with alpha-blockers or CYP3A4 inhibitors, can usually be managed with dose adjustments and monitoring.
For more on how Tadalafil works in the body, read our mechanism of action guide. For side effect information, see our Tadalafil side effects guide. And when you're ready to fill your prescription, Medfinder can help you find it in stock near you.
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