Supplements and Carbamazepine.
Carbamazepine, sold under the brand name Tegretol, is an antiepileptic drug. Several agents in this class are strong CYP inducers or inhibitors.
Carbamazepine is an antiepileptic medicine. The class is heterogeneous. Enzyme inducers (carbamazepine, phenytoin, phenobarbital) drop plasma levels of many medicines given alongside. Enzyme inhibitors (valproate) raise them. The newer agents (levetiracetam, lacosamide) have quieter interaction profiles. The supplement interactions of greatest clinical importance. St John's Wort is excluded with the inducer antiepileptics on top of an already complex CYP picture. Folate at high doses competes with the folate depletion that antiepileptics drive, in a way that needs neurology team input rather than community pharmacy. Calcium and vitamin D status matter because inducer antiepileptics drive bone density loss over years; the SANAD bone substudy data is the relevant evidence base. Pregnancy planning on an antiepileptic regimen always runs through the neurology team, because of folate timing and the teratogenicity profile specific to each agent (valproate carries the highest, levetiracetam much lower).
Below are the 4 documented pairs we have explicitly assessed against Carbamazepine in the Distil database: 4 amber. The pairs cluster around 4 mechanisms: Folate-anticonvulsant (two-way), CYP induction, CYP3A4 inhibition, and Drug depletes the supplement. Every call is cited to either a clinical reference (PMID) or the British National Formulary. Anything not on this list is either still to be assessed or beyond our database scope. The checker beneath surfaces assessments by supplement, and the missing-item form at the bottom of the page routes any uncatalogued supplement into our next curation pass.
Documented interactions
Folate-anticonvulsant (two-way)
Carbamazepine tends to lower folate levels over time, so people on it for a long time often run low on folate, which can also push up a blood marker called homocysteine. This usually works in the direction of needing folate rather than avoiding it, and folate is often supplemented on purpose in people on carbamazepine. As with other epilepsy medicines, it is sensible to start folate with your prescriber's knowledge so your levels and seizure control can be kept under review. Let whoever manages your epilepsy know before you start or stop folate.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
CYP induction
Carbamazepine is a strong enzyme-inducer that already speeds up its own breakdown, and St John's Wort works the same way. In the one controlled study, adding St John's Wort did not lower carbamazepine levels further, but combining two enzyme-inducers is still best avoided without specialist input, especially when carbamazepine is being started or its dose changed. Do not start or stop St John's Wort while taking carbamazepine without telling whoever prescribes it.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
CYP3A4 inhibition
Resveratrol can raise blood levels of carbamazepine by slowing how the body clears it, which may increase side effects such as dizziness, drowsiness, or unsteadiness. Carbamazepine has a narrow safe range, so tell your epilepsy or prescribing team before taking resveratrol.
Reviewer-flagged: awaiting clinical-reviewer sign-off.
Drug depletes the supplement
Carbamazepine speeds up the liver enzymes that break vitamin D down, so people on it for a long time tend to have lower vitamin D levels and, over years, a higher risk of weaker bones. This works the opposite way to most interactions: the medicine lowers your vitamin D rather than the supplement affecting the medicine. Taking a vitamin D supplement is generally the recommended response, and many prescribers check vitamin D and bone health in people on long-term carbamazepine.
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.
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 methodologyWant this checked across everything you take?
This page checks the pairs you enter. The personalised Distil report goes further:
- the same graded, cited interaction check across your whole stack, not just the pairs you thought to type in
- where your current routine may be leaving you short of your goals
- the evidence-backed compounds worth adding, and the ones worth dropping
It's a paid report: £79, or £49 for the first 25 customers. The interactions check is one section of it, and you can read a real one in full before you buy.
See a real sample reportSomething 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.