ED Medication Interactions: Nitrates, Alpha-Blockers, Alcohol and More

The most important thing to know about an ED medication is what it cannot be combined with. Here is the list, from the FDA labels.

Sildenafil, tadalafil and vardenafil belong to the same drug class, PDE5 inhibitors, and share the same interaction warnings. These come straight from their FDA prescribing information.^1,2,3

Never combine

Nitrates

Nitrates widen blood vessels, and so do PDE5 inhibitors. Together they can drop blood pressure to dangerous levels.¹ This includes nitroglycerin tablets, sprays and patches, isosorbide medications, and amyl nitrite inhalants sold as "poppers."

Guanylate cyclase stimulators

Riociguat, prescribed for pulmonary hypertension, is also contraindicated with PDE5 inhibitors for the same blood-pressure reason.¹

Use with caution

Alpha-blockers

Alpha-blockers such as doxazosin and tamsulosin, used for blood pressure or an enlarged prostate, also lower blood pressure. The labels advise caution and starting at a low dose.^1,2

Strong CYP3A4 inhibitors

Some medications slow the liver enzyme that breaks down PDE5 inhibitors, raising their levels in the blood. These include certain antifungals, HIV protease inhibitors and antibiotics. The labels call for a lower dose or limits on how often the ED drug is taken.^1,2

Other blood pressure medications

PDE5 inhibitors can add a small additional drop in blood pressure to other antihypertensives.¹

Alcohol

Drinking heavily while taking a PDE5 inhibitor can increase the chance of dizziness, a fast heartbeat, low blood pressure or fainting.²

Combinations of ED drugs

The sildenafil label states that combining it with other ED treatments has not been studied and is not recommended.¹ Some compounded products combine drugs anyway: Quattro combines three PDE5 inhibitors with apomorphine.⁴ That is a decision a clinician makes for an individual patient after reviewing every medication they take. Apomorphine adds its own considerations; nausea was its most common side effect in a clinical trial.⁵

What to tell the prescriber

Every prescription, including supplements and anything taken only occasionally. An incomplete medication list is the most common way an unsafe combination slips through.

Questions readers ask

Can I take sildenafil with nitroglycerin?

No. Nitrates in any form must never be combined with sildenafil, tadalafil or vardenafil because together they can cause a dangerous drop in blood pressure.

Can I drink alcohol with ED medication?

Heavy drinking with a PDE5 inhibitor can cause dizziness, low blood pressure or fainting. Ask the prescribing clinician what is safe for you.

Can I take ED medication with blood pressure pills?

Often yes, with caution. Alpha-blockers in particular need a careful dose. A clinician should review your full medication list.

Further reading

Part of our guide: How ED Medications Work: Timing, Food, Interactions and Combinations

• Sildenafil Headache: How Common Is It?
• Tadalafil With Alcohol: How Much Is Too Much?
• What Is Tadalafil Used For? The Three Approved Uses
• Tadalafil Brand Names: Which Brand Is Used for What