Tansy Safety: What You Need to Know Before Using It

Tansy (Tanacetum vulgare) looks harmless in a garden, but it contains a chemical called thujone that can cause real problems if you treat it like a harmless tea. People have used tansy for digestion, worms, and menstrual issues for centuries — but that history doesn’t make it safe. If you’re thinking about using tansy, knowing the risks and simple safety steps matters.

What makes tansy risky?

Thujone is the headline risk. It’s a neuroactive compound also found in wormwood and linked to seizures and nervous system symptoms at higher doses. Tansy can also irritate the skin, cause nausea or vomiting, and in rare cases harm the liver. Historically it was used to stimulate menstruation; that means it can trigger contractions and raise the risk of miscarriage.

Because of these effects, tansy isn’t just “a mild herb.” It’s concentrated in essential oils and extracts, where a tiny dose can become dangerously strong. Even dried-leaf tea can be unsafe if used often or in large amounts.

Practical safety tips

Avoid it if you are pregnant, breastfeeding, or planning pregnancy. Don’t give tansy to children or people with epilepsy — thujone can lower seizure threshold. If you have liver disease or take medication processed by the liver, check with a clinician before using any tansy product.

Never ingest tansy essential oil: essential oils are too concentrated and dangerous by mouth. If you try topical use, always dilute the oil in a carrier oil and do a small patch test first. Even then, stop if you get redness, itching, or a burning feeling.

If you want to try a mild tansy tea despite the warnings, keep it short-term and low-dose: one small cup, not daily for weeks. Save the product label and talk to a pharmacist or doctor who knows herbal interactions. Tansy can affect the nervous system and may interact with seizure medications, blood thinners, or drugs that stress the liver.

Learn to spot toxicity: dizziness, tremors, confusion, vomiting, breathing trouble, or seizures need immediate medical help. If someone swallows a concentrated tansy product, call your local poison control or emergency services and bring the container if you can.

If you want herbal help for digestive upset, nausea, or menstrual cramps but prefer safer options, consider ginger or peppermint for digestion and heat or gentle pain relievers for cramps—after checking with your healthcare provider. Chamomile can help some people with mild cramping or sleeplessness, though allergies are possible.

Tansy is a real herbal tool but one that comes with real risks. Treat it carefully, avoid concentrated forms, skip it during pregnancy or if you have seizures or serious liver issues, and always check with a healthcare professional before trying it internally.