A fatal overdose from chamomile tea is extremely unlikely. No human deaths from chamomile consumption have been documented in medical literature, and the herb has FDA “Generally Recognized as Safe” (GRAS) status as a food ingredient. That said, chamomile is not completely without risk. Large amounts can cause nausea and dizziness, and for certain people, particularly those on blood thinners, those with ragweed allergies, or those who are pregnant, chamomile in excess can cause real harm.
Why a Lethal Dose Is Essentially Impossible
Chamomile has been studied extensively for toxicity, and researchers have consistently found very low risk. Animal and insect studies show that chamomile’s essential oils and extracts are remarkably non-toxic to complex organisms. In clinical trials, standardized chamomile extract has been given to humans at doses up to 1,500 mg daily for months at a time with minimal side effects. To put that in perspective, a typical cup of chamomile tea contains far less active compound than a 1,500 mg capsule of concentrated extract.
A systematic review covering 72 clinical trials and 11 case reports found no reports of organ damage, poisoning, or death from chamomile. The side effects that did appear in trials were mild: occasional nausea, dizziness, and rare allergic reactions. You would almost certainly vomit long before you could drink enough chamomile tea to reach a dangerous concentration of its active compounds.
What Happens If You Drink Too Much
The most common effects of excessive chamomile are nausea and drowsiness. Chamomile contains a compound called apigenin that binds to the same brain receptors targeted by anti-anxiety medications like benzodiazepines. This is what gives chamomile its calming, sleep-promoting effect. In large quantities, that sedation becomes more pronounced, leaving you groggy or lightheaded rather than pleasantly relaxed.
According to the National Institutes of Health, side effects from chamomile are uncommon overall, but when they do occur, nausea, dizziness, and allergic reactions are the primary concerns. These symptoms typically resolve on their own once you stop consuming chamomile.
The Real Danger: Allergic Reactions
The most serious documented risks from chamomile are allergic, not toxic. If you’re allergic to plants in the daisy family (ragweed, mugwort, chrysanthemums), you may cross-react to chamomile. In a study of 14 patients with immediate allergic reactions to chamomile, some experienced life-threatening anaphylaxis. Eleven of those patients were also sensitized to mugwort pollen, and eight to birch pollen, confirming that shared proteins between these plants trigger the immune response.
Of the 11 case reports included in one systematic review, six involved allergic reactions to chamomile, and three of those were anaphylactic reactions. These are rare, but they represent the closest thing to a genuine chamomile emergency in the medical record. If you’ve never had chamomile before and you have known pollen or plant allergies, start with a small amount.
Dangerous Interactions With Medications
Where chamomile poses a more practical risk is in combination with other substances. Because apigenin acts on the same brain receptors as sedatives, chamomile can amplify the effects of alcohol, sleep aids, and anti-anxiety medications. Drinking several cups of strong chamomile tea on top of a sedative could produce excessive drowsiness or impaired coordination beyond what either substance would cause alone.
The more concerning interaction involves blood thinners. Chamomile naturally contains coumarins, a family of compounds with mild blood-thinning properties. For most people, this is harmless. But if you take warfarin or a similar anticoagulant, heavy chamomile consumption can push your blood’s clotting ability below safe levels. A case report published in the Canadian Medical Association Journal described a patient on warfarin whose blood clotting measurements climbed to dangerously high levels after using chamomile products. The coumarins in chamomile appeared to work synergistically with the medication, effectively making the drug stronger than intended.
Chamomile During Pregnancy
Chamomile has a long history of traditional use as a uterine stimulant. Research confirms this is not just folklore: chamomile has been shown to promote uterine contractions and has even been studied as a tool for inducing labor in post-term pregnancies. It appears to work by reducing stress hormones that inhibit contractions while supporting the body’s natural labor signals.
This means that during earlier stages of pregnancy, concentrated or excessive chamomile could theoretically increase the risk of premature contractions. An occasional cup of weak chamomile tea is generally considered low-risk, but regularly drinking large amounts or taking chamomile supplements during pregnancy is a different matter. The uterine-stimulating effect becomes more relevant the higher the dose.
How Much Is Considered Safe
There is no official upper limit set by the FDA for chamomile consumption. Clinical trials have safely used concentrated chamomile extract at 500 to 1,500 mg per day for up to 34 weeks in adults. Participants who couldn’t tolerate the minimum dose of 500 mg daily were removed from studies, suggesting that’s roughly the threshold where some people start noticing unwanted effects from concentrated forms.
For chamomile tea, one to three cups per day is the range most commonly consumed and studied without notable problems. The concentration of active compounds in brewed tea is substantially lower than in capsules, so the margin of safety is wider. If you’re healthy, not pregnant, not on blood thinners or sedatives, and not allergic to ragweed-family plants, even a generous chamomile habit is unlikely to cause you any trouble.