Drug Interactions and the Nitrate Contraindication
PDE5 Inhibitors, Nitrates, Alpha-Blockers, and Poppers
Evidence grade 5 of 5, Settled. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Absolute nitrate contraindication on PDE5 inhibitor labels
Reference only. Not medical advice.
What can go wrong
Absolute contraindication: PDE5 inhibitors with any nitrate or nitrite donor, prescription nitroglycerin or isosorbide, and recreational amyl/alkyl nitrite 'poppers', can cause life-threatening hypotension. After a PDE5 inhibitor is taken, nitrates must be withheld for a drug-specific interval (longer for long-acting tadalafil). Alpha-blockers require caution and timing separation. The danger is acute and unforgiving, which is why prescriber screening exists and why hidden PDE5 inhibitors in supplements (see Supplement Adulteration) are so hazardous.
This is something to take to a clinician. The Atlas can tell you what is known about drug interactions and the nitrate contraindication in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
The combination of PDE5 inhibitors and nitrates is an absolute contraindication, together they can cause profound, potentially fatal hypotension. This includes prescription nitrates (nitroglycerin, isosorbide) and recreational nitrites ('poppers'). PDE5 inhibitors also potentiate alpha-blockers, requiring caution and dose separation. These are well-defined, label-level interactions that prescriber screening is designed to catch and that self-treatment bypasses.
The one combination that can kill: PDE5 inhibitors plus nitrates.
What people take it for
What it is taken for. Approval, where it exists, covers only some of these.
How it works
Nitrates and nitrites donate nitric oxide, which raises cGMP and relaxes vascular smooth muscle. PDE5 inhibitors block the enzyme that degrades cGMP. Given together, cGMP accumulates unchecked, producing synergistic, profound vasodilation and a precipitous drop in blood pressure that can be fatal. Alpha-blockers (used for hypertension and BPH) add their own vasodilatory/hypotensive effect, so combination with PDE5 inhibitors requires dose separation and caution.
Safety in detail
PDE5 inhibitors must never be combined with nitrates or nitrite 'poppers', the combination can cause fatal hypotension. Erectile dysfunction therapy requires evaluation by a qualified physician who can screen for these interactions. Self-treatment bypasses this safeguard.
- PDE5 inhibitor + nitrate/nitrite is an absolute contraindication (fatal hypotension)
- Includes prescription nitrates and recreational 'poppers'
- Mechanism: unchecked cGMP accumulation and synergistic vasodilation
- Alpha-blockers cause additive hypotension, caution and dose separation
- Nitrate-free interval is drug-specific (longer for tadalafil)
- Hidden PDE5 inhibitors in supplements make this interaction unpredictable
What people get wrong
Often saidWaiting a few minutes makes nitrates safe after an ED pill
ActuallyThe nitrate-free interval is drug-specific and can be long, especially for tadalafil. In an emergency, this interaction limits the use of life-saving nitroglycerin.
Often saidPoppers are recreational, not real drugs, so they are fine with ED pills
ActuallyPoppers are nitrites and carry the same fatal interaction with PDE5 inhibitors as prescription nitrates.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
At a glance
- Absolute contraindication
- PDE5 inhibitor + any nitrate/nitrite
- Mechanism
- Synergistic cGMP-mediated vasodilation
- Also caution
- Alpha-blockers (additive hypotension)
- Recreational nitrites
- 'Poppers', same fatal interaction
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Drug Interactions and the Nitrate Contraindication. A short entry is not a safe entry.
- Timeline. We have not built the dated record of research and regulatory events.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
- Where we land. We have not taken a position on this yet.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
Cheitlin et al., ACC/AHA expert consensus on sildenafil and nitrates1999
Established the absolute contraindication of sildenafil with organic nitrates due to potentiated hypotension
PDE5 inhibitor product labeling (sildenafil, tadalafil, vardenafil, avanafil)ongoing
Carry an absolute contraindication with nitrates and cautions with alpha-blockers