Medication · methylxanthine

Supplements and Theophylline.

Not yet catalogued in the Distil interactions database. We surface that distinction explicitly.

Theophylline, sold under the brand names Slo-Phyllin, Uniphyllin, is a methylxanthine bronchodilator. The therapeutic window is narrow.

Theophylline is a methylxanthine bronchodilator. In current UK practice that mostly means theophylline (less commonly aminophylline). The therapeutic window is narrow. Plasma levels are monitored because both efficacy and toxicity (nausea, tremor, arrhythmia, seizure) sit close together. The supplement surface is large because theophylline is heavily CYP1A2 metabolised. Smoking induces CYP1A2 and drops plasma levels, pushing doses higher. On smoking cessation, levels rise and doses need adjustment. Caffeine is a methylxanthine itself and stacks additively at high intake. Several supplements influence CYP1A2. Cruciferous vegetables and concentrated extracts modestly induce. Certain quinolone pathway compounds inhibit. The class is much less prescribed today than thirty years ago, since inhaled beta-2 agonists and inhaled corticosteroids dominate asthma and COPD treatment. But theophylline remains in some specialist prescribing.

We have not yet completed an explicit assessment of supplement interactions with Theophylline in the Distil database. That is different from saying nothing exists. We surface this distinction deliberately: the Distil checker tells you when we have explicitly assessed a pair and when we have not, because both are useful information. If you take Theophylline alongside a supplement, the checker below will surface anything already in our database, and the missing-item form at the bottom of the page routes uncatalogued pairs into our next curation pass.

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 (food-supplement interactions only; for drug-drug interactions, the BNF is authoritative). Use the checker below to surface any supplement, and submit a missing item if you take something we have not catalogued.

Loading database stats…

For adults over 18. This tool gives evidence-graded information, not medical advice. Always discuss changes with your GP, especially if you take any medication, are pregnant, breastfeeding, or have a serious health condition.

Anything we should know? (optional)

Pick any that apply. We adjust the findings where context changes the answer.

Your supplements

Type the supplement name. Click each match to add it.

Your medications

Brand or generic name works. Click each match to add it.

How we decide

How we grade severity, choose what's in scope, and what we exclude.

Every call on this page is reasoned. We publish the full rubric for severity tiers, the medication inclusion logic, the evidence grades we accept, and what we deliberately leave out. About three thousand words. Worth reading once if you use this tool more than occasionally.

Read the full methodology

Something missing?

If a supplement or medication you take isn't in our autocomplete, tell us. We go through what people flag every week and add what's missing.

Thanks, that's logged. We go through flagged items every week.

Distil's interactions database is reviewed and updated every quarter. We grade evidence transparently and publish our methodology, including every database change, at /about/methodology. This tool is information, not a substitute for clinical judgement. If you take medication and supplements together, your GP or pharmacist can review your full regimen against your medical history. If you want a full personalised stack reasoned against this same database, the Distil report is the next step up.