Tap (draught) and unpasteurised beer — interactions

The precise version of "avoid beer". Shulman et al. measured Canadian tap beers and found some with tyramine high enough to matter, while bottled and canned beers were consistently low. The rule is about pasteurisation and ongoing fermentation, not alcohol.

Also known as: draught beer, draft beer, home-brew, cask ale, unpasteurised beer. Category: food.

What it does, mechanism by mechanism

Dietary tyramine load — provides, variable

Food that carries pressor amines produced by bacterial decarboxylation during ageing or fermentation. Harmless when gut and liver MAO-A destroy it. Not harmless when that enzyme is blocked.

Bottled/canned commercial beer: low, and two standard drinks are generally regarded as acceptable in modern MAOI guidance. Tap, cask and home-brewed beer: unpredictable and occasionally high. Tailor et al. re-analysed the classic phenelzine + tap beer hypertensive case and confirmed pressor amines in the beer.

Sources: Shulman KI 1997, Tailor SAN 1994, Gillman PK 2018 · more on Dietary tyramine load

Specific combinations

What a clean result means here

A clean result means NO DOCUMENTED INTERACTION IN THIS DATASET. It does not mean safe, and it is not a clearance. Most substances are not in this dataset at all, and for many pairs that are, nobody has ever studied the combination.

In this dataset

  • Monoamine oxidase inhibition (prescription MAOIs, RIMAs, linezolid, methylene blue, harmala alkaloids)
  • Serotonergic drugs and the serotonin-toxicity mechanism
  • Dietary tyramine and L-dopa loads
  • The major cytochrome P450 pathways: CYP3A4, CYP2D6, CYP1A2, CYP2C9, CYP2C19 — inhibition and induction
  • P-glycoprotein inhibition and induction
  • 11β-HSD2 inhibition (the licorice mechanism) and the potassium consequences that follow it
  • QT prolongation as an additive pharmacodynamic axis
  • Culinary seasonings and common foods with documented pharmacological activity
  • A selected set of narrow-therapeutic-index drugs where those shifts matter most

Not in this dataset

  • Any substance not named in this dataset — which is most substances. There are tens of thousands of marketed drugs and this table holds fewer than a hundred entries.
  • Phase-2 conjugation (UGT, SULT, NAT2, COMT) except where a specific entry names it. The oilahuasca corpus turns heavily on phase 2 and this engine models it only in passing.
  • Pharmacogenomics. CYP2D6 and CYP2C19 are strongly polymorphic; a poor metaboliser and an ultra-rapid metaboliser can have opposite outcomes from the same pair, and this engine does not know your genotype.
  • Dose, timing, duration, formulation and route — all of which change whether a documented interaction is clinically real for you.
  • Renal and hepatic impairment, age, pregnancy, and body composition.
  • Additive sedation, respiratory depression, bleeding risk, hypoglycaemia and most other pharmacodynamic axes beyond the ones listed above.
  • Herb–herb interactions outside the named entries, and essentially the whole botanical world: most plants have no interaction literature at all.
  • Allergy, intolerance, and contamination or adulteration of unregulated products.
  • Anything published after the last-reviewed date below.

72 substances, 20 mechanisms, 64 citations. Last reviewed . Primary literature (every DOI resolved against the Crossref API) and FDA drug labelling. There is no free, openly-licensed, comprehensive drug-interaction dataset to draw on; NLM retired its Drug Interaction API on 2024-01-02 and DrugBank's interaction set is a commercial licence.

References

  1. Shulman KI, Tailor SAN, Walker SE, Gardner DM (1997). Tap (Draft) Beer and Monoamine Oxidase Inhibitor Dietary Restrictions. The Canadian Journal of Psychiatry. doi:10.1177/070674379704200311
  2. Tailor SAN, Shulman KI, Walker SE, Moss J, Gardner D (1994). Hypertensive Episode Associated with Phenelzine and Tap Beer — A Reanalysis of the Role of Pressor Amines in Beer. Journal of Clinical Psychopharmacology. doi:10.1097/00004714-199402000-00002
  3. Gillman PK, Feinberg SS, Fochtmann LJ (2018). A reassessment of the safety profile of monoamine oxidase inhibitors: elucidating tired old tyramine myths. Journal of Neural Transmission. doi:10.1007/s00702-018-1932-y

Every DOI above was resolved against the Crossref API on 2026-09-09 and the returned title checked against the one printed here. Three DOIs in the first draft resolved to real but different papers and were corrected before publication.

Last reviewed . All interaction pages.