What are the side effects of drinking too much herbal tea?

What are the side effects of drinking too much herbal tea?

Herbal tea is a group of different plants, so there is no single list. Official bodies describe risks plant by plant. The National Center for Complementary and Integrative Health (NCCIH) says chamomile is likely safe in amounts commonly found in teas, with uncommon side effects that may include nausea, dizziness and allergic reactions, and rarely severe reactions including anaphylaxis. People allergic to related plants such as ragweed, chrysanthemums, marigolds or daisies may be more likely to react.

Can herbal teas affect medicines?

Yes, some can. An NCCIH clinical digest says most herb-drug interactions identified in current sources are hypothetical, but it lists examples:

• St. John’s wort: documented interactions with cyclosporine, indinavir, oral contraceptives, warfarin, digoxin and benzodiazepines.
• Ginkgo: with warfarin, linked to increased risk of major bleeding.
• Green tea extract: can lower blood levels of atorvastatin; at high doses it may lower nadolol levels.
• Goldenseal: lowered metformin levels about 25 percent in healthy adults in one study.
• Chamomile: reported interactions with warfarin, and possibly birth control pills.

The digest names drugs with a narrow therapeutic index, such as warfarin, digoxin and cancer chemotherapy drugs, as needing the most care. Some of these findings concern supplements and extracts rather than tea, so check with a pharmacist about your own case.

What about pregnancy?

NCCIH says little is known about whether chamomile is safe in pregnancy or while breastfeeding. For other herbs we found no figure we could verify, so ask a midwife or doctor before drinking herbal teas daily when pregnant.

What symptoms should you watch for?

• Rash, itching, swelling or breathing trouble: stop and get medical help urgently.
• Nausea or dizziness after a new tea: stop and see if it passes.
• Unusual bleeding or bruising if on blood thinners: contact your doctor.

How can you reduce risk?

• Vary teas instead of drinking one blend all day.
• Read the ingredient list, since blends hide strong herbs.
• Tell your pharmacist which herbal teas you drink.

This is general information, not medical advice.