NAC and medications.
NAC is in the Distil supplement database, evidence Grade A. The page below lists every medication we have explicitly assessed it against.
NAC, or N-acetyl cysteine, is a precursor to glutathione, the body's main internal antioxidant. Its best-supported use is respiratory, at Grade A, and where that evidence comes from matters: every trial behind it was run in people who already have chronic obstructive pulmonary disease or chronic bronchitis. A Cochrane review of 38 trials in 10,377 people, which pooled NAC with similar agents, found that the treated group tended to have a flare-up less often, with little effect on lung function or quality of life, and a NAC-specific analysis found that benefit at high doses only. The trials we hold do not describe what NAC does for healthy lungs. The evidence is Grade B for mood, from a meta-analysis of five randomised trials in people being treated for a diagnosed psychiatric condition, where depressive symptoms improved modestly against placebo. We do not grade it for autism: the trials there are all in children, and the largest found no benefit on any measure. We do not recommend NAC for liver health. The trial cited for it was open-label, gave every arm the same second medicine, and reported no significant difference between its groups. A later trial that gave NAC without a second medicine, in 60 people with fatty liver disease, found no benefit on oxidative stress, blood sugar handling, liver fat or fibrosis. The usual dose is 600mg twice daily. The interactions worth knowing: NAC has an effect on clotting through von Willebrand factor, so as a precaution it is worth pausing a couple of weeks before any planned surgery, and worth a mention to your GP if you take a blood thinner. The evidence we hold for that effect is at doses far higher than a supplement provides, with no human bleeding data in our records at supplement doses, so treat it as a conservative flag rather than an established risk. It can also strengthen the effect of glyceryl trinitrate (GTN), so if you use a GTN spray or patch, watch for dizziness or worse headaches and tell your GP or pharmacist. A small trial in older adults found that glycine and NAC taken together, as GlyNAC, raised glutathione compared with placebo. Take it with food to limit stomach upset, and expect a harmless rotten-egg smell in urine at high doses.
Below are the 2 documented pairs we have explicitly assessed for NAC: 2 caution. The pairs cluster around 1 mechanism: Additive vasodilation. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not listed here is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by medication, and the missing-item form at the bottom of the page routes any uncatalogued medication into our next curation pass.
Documented interactions
Last reviewed 14 June 2026. Each interaction below lists the evidence its assessment drew on: some rest on studies of the exact pair, others on mechanism evidence, where a citation may support one part of the reasoning rather than the exact combination. The evidence line on each entry says which.
Additive vasodilation
Caution Does NAC interact with Glyceryl trinitrate?
Taking NAC with glyceryl trinitrate (GTN) can make GTN act more strongly, which may mean a more pronounced headache and a larger drop in blood pressure than GTN alone, because NAC is a sulfur-rich compound and GTN needs sulfur groups in the body to work. If you use a GTN spray or patch and take NAC, watch for dizziness, faintness on standing, or worse headaches, and tell your GP or pharmacist so they can review the timing or doses.
Evidence: Supported by human study data.
Caution Does NAC interact with Isosorbide mononitrate?
Taking NAC with isosorbide mononitrate may make the nitrate act more strongly, which can mean a more pronounced headache and a larger drop in blood pressure than the nitrate alone, because NAC is a sulfur-rich compound and nitrate medicines rely on sulfur groups in the body to work. If you take isosorbide mononitrate and want to use NAC, watch for dizziness, faintness on standing, or worse headaches, and tell your GP or pharmacist so they can review the timing or doses.
Evidence: No direct study of this exact combination yet; the caution rests on a plausible mechanism or on reports involving a related medicine.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
What this list does not say. Pairs not flagged here are not implicitly safe. They are either not yet in our database, or fall outside our inclusion scope. Use the checker below to surface any medication, and submit a missing item if you take something we have not catalogued.
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How the checker decides
Every result has a source
Each pair we have assessed is cited to a published study (PMID) or the British National Formulary, so you can read the source yourself.
Four kinds of answer
Severe, caution, no known interaction, and not yet assessed. A pair we have not assessed is never shown as clear.
- Severe
- Caution
- No known interaction
- Not yet assessed
Nothing in our data is not a clearance
When nothing in our data records a problem with a pair, the result says no known interaction at typical doses, which is not a clearance: your pharmacist or GP can check the pair against your full medical history.
A full supplement review, built around you, not a generic stack.
The free checker answers one interaction question at a time. A Distil report reviews the bigger picture: your goals, diet, medications, current supplements and any blood results you provide, then shows what appears worth keeping, changing, adding or leaving out.
- what your diet already covers, so you are not adding a capsule for something food is already handling
- which evidence-graded compounds are worth considering for your goals, and which were considered but left out
- what to keep, change or stop from what you already take, plus the order to introduce anything new
- how your medications and complete supplement stack fit together, with daily timing and a clear point for reassessment
The interaction check is one section of the full report. You also get the reasoning behind each recommendation and the evidence references used.
£49 until 30 June 2027 · £79 from 1 July 2027.
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