Drug & supplement interaction

N-acetyl Cysteine (nac) + Nitroglycerin

Nitroglycerin brand names: Nitrostat, Nitrogard SR, Sustachron, Nitro-Bid, Sustachron ER Buccal, and others.

Major Interaction
Medically reviewed by · Updated September 2026
The bottom line Major

N-acetyl Cysteine (nac) has a major interaction with Nitroglycerin. N-acetyl cysteine can increase the risk for hypotension and headaches when taken with intravenous or transdermal nitroglycerin.

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

N-acetyl Cysteine (nac) and Nitroglycerin

Here is the interaction we found between these two, with the evidence behind it.

Major

NITROGLYCERIN

N-acetyl cysteine can increase the risk for hypotension and headaches when taken with intravenous or transdermal nitroglycerin.
Clinical research shows that concomitant administration of N-acetyl cysteine and intravenous or transdermal nitroglycerin can cause severe hypotension and intolerable headaches. Furthermore, in vitro research suggests that N-acetyl cysteine increases the anticoagulant activity of nitroglycerin.
Severity Major Likelihood Probable Evidence B

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist with these two together: NAC tends to boost the blood-vessel-relaxing effect of nitroglycerin. Nitroglycerin works by releasing nitric oxide to open up your vessels, and NAC supplies cysteine that helps make that happen more readily. So instead of canceling each other out, they pull in the same direction.

What that can look like in real life is your blood pressure dropping too low (feeling dizzy, lightheaded, or faint when you stand up) and worse pounding headaches, which nitroglycerin already tends to cause. This has shown up mostly with IV and patch/ointment forms in clinical studies, so it's worth taking seriously. Please don't start, stop, or change anything on your own. Loop in your pharmacist or doctor first so they can check your blood pressure and your plan.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Ardissino D, Merlini PA, Savonitto S, et al. Effect of transdermal nitroglycerin or N-acetylcysteine, or both, in the long-term treatment of unstable angina pectoris. J Am Coll Cardiol 1997;29:941-7. PubMed
  2. Horowitz JD, Henry CA, Syrjanen ML, et al. Nitroglycerine/N-acetylcysteine in the management of unstable angina pectoris. Eur Heart J 1988;9:95-100. PubMed
  3. Iversen HK. N-acetylcysteine enhances nitroglycerin-induced headache and cranial arterial responses. Clin Pharmacol Ther 1992;52:125-33. PubMed
  4. Loscalzo J. N-Acetylcysteine potentiates inhibition of platelet aggregation by nitroglycerin. J Clin Invest. 1985;76(2):703-8. PubMed
  5. Chirkov, Y. Y. and Horowitz, J. D. N-Acetylcysteine potentiates nitroglycerin-induced reversal of platelet aggregation. J Cardiovasc.Pharmacol 1996;28(3):375-380. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

N-acetyl Cysteine (nac) Also Interacts With Other Medications

N-acetyl Cysteine (nac) has 293 moderate known drug interactions in our database — the Nitroglycerin one above is one of them. If you take anything else, check it against the full list below.

Moderate 293 No known interaction 2,537 (incl. Nitroglycerin)
Taking anything else?

Check Another of Your Medications Against N-acetyl Cysteine (nac)

Covers the 2,830 medications we’ve checked against N-acetyl Cysteine (nac). Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Nitroglycerin

This page covers N-acetyl Cysteine (nac) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Nitroglycerin page lists 26 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Mistletoe (major), Coleus (major), Hawthorn (major) and Beer (moderate).

By severity: 5 major · 11 moderate · 10 minor.

From our pharmacist’s overview on the Nitroglycerin page

“Nitroglycerin (Nitrostat, Nitro-Bid) exists to open blood vessels quickly during angina, so a supplement that also drops blood pressure, or one that fights the drug's effect, is not a small matter, and this list warrants real care before you add to it. The most serious entries pull in two directions.”

Reviewed by 2 · Jul 18, 2026

Open the Nitroglycerin interaction page

One more smart check

Taking N-acetyl Cysteine (nac) as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,554 real supplement products containing N-acetyl Cysteine (nac), each one broken down to its full ingredient list — and combination products often carry several ingredients besides N-acetyl Cysteine (nac). Your product may carry other ingredients that interact with Nitroglycerin too, on top of N-acetyl Cysteine (nac) — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where N-acetyl Cysteine (nac) and Nitroglycerin Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement N-acetyl Cysteine (nac)
Top 5%

#62 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Nitroglycerin
Top 10%

#216 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About N-acetyl Cysteine (nac)

What is N-acetyl Cysteine (nac)?

N-acetyl Cysteine (nac)
  • Thinning mucus in lung conditions
  • Acetaminophen (Tylenol) overdose treatment
  • Antioxidant and glutathione support
  • Liver support
  • Respiratory health

N-acetyl cysteine (NAC) is a supplement form of the amino acid cysteine and a building block for the antioxidant glutathione. It has well-established prescription uses for acetaminophen overdose and thinning mucus, but evidence for many over-the-counter uses is still limited. It is generally well tolerated, but you should check with a pharmacist or doctor before starting it.

Read the full N-acetyl Cysteine (nac) monograph & all interactions
Medication

About Nitroglycerin Topical

What Is Nitroglycerin Topical Used For?

Brand names: Nitrostat, Nitrogard SR, Sustachron, Nitro-Bid, Sustachron ER Buccal, Nitroglyn, Nitro Time, Nitrong, Nitrogard, Nitrocine Timecaps, Nitroquick, Rectiv, Gonitro

Rectiv (nitroglycerin ointment 0.4%, applied rectally) is specifically indicated to treat moderate to severe pain associated with chronic anal fissure — a small tear in the lining of the anal canal.

Nitro-Bid (nitroglycerin ointment, applied to the skin) has been used to reduce exercise-related angina (chest pain brought on by physical activity). These are distinct products with separate uses; they are not interchangeable.

See full Nitroglycerin Topical drug information
Keep checking

Other Drugs & N-acetyl Cysteine (nac)

Browse every other medication we’ve checked against N-acetyl Cysteine (nac) — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
293Moderate
0Minor
2,536No known interaction
293 Moderate 2,536 No interaction
Moderate

293 interactions

Showing 60 of 293 moderate interactions — see all 293 on the N-acetyl Cysteine (nac) page.

No interaction 2,536 drugs checked — show the list

We also checked N-acetyl Cysteine (nac) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,536 medications checked with no known interaction — see the full N-acetyl Cysteine (nac) list.

See the full N-acetyl Cysteine (nac) interactions page
See every supplement checked against Nitroglycerin, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
N-acetyl Cysteine (nac) monograph › Uses, safety, and every drug interaction in one place Nitroglycerin supplement interactions › Every supplement checked against Nitroglycerin, ranked by severity Nitroglycerin Topical drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking N-acetyl Cysteine (nac) and Nitroglycerin Together: Common Questions

Can you take N-acetyl Cysteine (nac) with Nitroglycerin?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the N-acetyl Cysteine (nac) and Nitroglycerin interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.