Cinnamon and medications: what to check

Cinnamon's most relevant interaction risk is with medications that already lower blood sugar, because some research has found a blood-sugar-lowering effect in people who already have it elevated. A second, less-tested concern involves the liver, particularly in combination with cassia cinnamon's coumarin content and other liver-processed medications.

Medications that lower blood sugar

If you take insulin, metformin, a sulfonylurea, or any other medication that lowers blood sugar, ask your doctor before adding a cinnamon supplement. Some research has found a blood-sugar-lowering effect in people who already have it elevated (see cinnamon benefits for the specifics, including where the effect didn't hold up), and combining two glucose-lowering effects is a reason for caution, not a reason to expect a bigger benefit.

Medications processed by the liver

In a 2015 case report, a woman developed acute hepatitis after combining a long-term statin with a cinnamon supplement, and the authors attributed it to the combination rather than either substance alone — one case, not a proven pattern, but the clearest documented example of cinnamon plus a specific drug class causing a problem, which is why anyone on a statin or any other medication their doctor has flagged as hard on the liver should ask a doctor before adding cinnamon, especially a cassia-based product.

Blood thinners

Cinnamon's coumarin is chemically related to warfarin, a prescription blood thinner, though it's a different compound and hasn't been shown in a controlled trial to affect bleeding risk or blood-clotting tests in people taking cinnamon supplements. No trial has tested this combination directly — the concern is mechanistic, not measured — which is exactly the kind of gap worth raising with a doctor rather than assuming either way. Ask before combining cinnamon with warfarin or any other blood thinner.

Other supplements

We haven't found documented research on cinnamon combined with other common supplements. If you take several supplements together, particularly more than one marketed toward blood sugar, mention all of them to a doctor or pharmacist rather than assuming they simply add up harmlessly.

Questions people ask

Can I take cinnamon with metformin?

Ask a doctor first. Some research suggests cinnamon and metformin could have an additive glucose-lowering effect, and combining them without medical guidance isn't something to do on your own.

Does cinnamon interact with blood thinners?

No controlled trial has tested it directly. The concern comes from coumarin's chemical relationship to warfarin, and it's a reasonable enough question that it's worth asking a doctor before combining the two, even without a trial confirming a problem.

Can you take cinnamon and berberine together?

Both have been studied for an effect on blood sugar, so the same additive-effect caution above applies. Ask a doctor, particularly if you're also taking a medication for blood sugar.

Related reading: who should not take cinnamon and cinnamon side effects.