Chamomile tea is safe for most adults, but several groups face real risks from drinking it. People with ragweed allergies, those on blood thinners, pregnant women, infants under one year, and anyone taking sedatives or certain prescription medications should either avoid chamomile or use it with caution. The FDA classifies chamomile as “generally recognized as safe” for use in food, but that designation doesn’t account for individual health conditions or drug interactions.
People With Ragweed or Daisy Allergies
Chamomile belongs to the same plant family as ragweed, daisies, and chrysanthemums. If you’re allergic to any of these plants, your immune system may react to chamomile the same way. A systematic review of adverse event case reports found that more than half of the documented reactions to chamomile were allergic in nature, ranging from brief bouts of acute rhinitis to full anaphylaxis. Three of the six allergy-related cases involved anaphylactic reactions, which can be life-threatening.
The cross-reactivity means you don’t need a prior chamomile exposure to have a reaction. If ragweed pollen triggers your symptoms during allergy season, chamomile tea could provoke a similar response year-round.
People Taking Blood Thinners
Chamomile contains natural compounds similar to coumarins, the same class of chemicals that forms the basis of warfarin. When chamomile and warfarin are used together, the anticoagulant effect can intensify beyond the therapeutic range. In one documented case, a 70-year-old woman on warfarin developed serious internal bleeding after using chamomile products for cold symptoms. Her other medications were reviewed and ruled out as contributing factors.
The interaction likely works through two pathways. The coumarin-like substances in chamomile (herniarin and umbelliferone) may amplify warfarin’s blood-thinning action directly. Chamomile also inhibits certain liver enzymes responsible for breaking down drugs, which could slow the clearance of warfarin from your body. If you take warfarin, aspirin, or other anticoagulant or antiplatelet medications, chamomile tea is worth avoiding entirely.
People Scheduled for Surgery
Because of its coumarin-like compounds and potential effect on clotting, major health systems recommend stopping chamomile at least two weeks before any surgery or dental procedure. Mount Sinai’s guidelines specifically advise this two-week window. The concern is straightforward: even a mild blood-thinning effect during surgery increases the risk of excessive bleeding when you need your clotting system working at full capacity.
Pregnant Women
There is not enough clinical evidence to confirm chamomile is safe during pregnancy. A recent systematic review concluded that developing practice recommendations on chamomile use in pregnancy simply isn’t possible with current data. The research that does exist raises concerns. One study of 392 women found that the 37 who used chamomile had a notably higher frequency of miscarriage (21.6%) and preterm labor compared to those who didn’t. A separate case report linked chamomile infusions to premature constriction of a key fetal blood vessel in two pregnant women.
There’s an additional risk with chamomile tinctures specifically: they can contain up to 12% grain alcohol, which should be avoided entirely during pregnancy. Even standard chamomile tea, though, carries enough uncertainty that most sources recommend skipping it until after delivery.
Infants Under One Year
In many cultures, chamomile tea is a traditional remedy for infant colic. But chamomile poses a specific and serious risk to babies: botulism. Researchers analyzed 200 chamomile samples and found that 7.5% were contaminated with botulinum spores. Loose chamomile sold by weight at herbal stores carried significantly higher contamination rates than chamomile packaged in tea bags.
Infant botulism affects babies younger than 52 weeks because their gut flora isn’t mature enough to compete with the bacteria. Adults can handle trace amounts of botulinum spores without issue, but in an infant’s digestive tract, those spores can germinate and produce toxin. The spore loads detected were small (roughly 0.3 to 0.4 spores per gram), but for an infant, even low exposure is a legitimate risk.
People on Sedatives or Anti-Anxiety Medication
Chamomile’s calming effect isn’t just folklore. It contains a flavonoid called apigenin that produces sedation by acting on the same brain receptors targeted by benzodiazepines and other sedative medications. These are the GABA receptors, the system your brain uses to dial down nerve activity.
If you’re already taking a medication that works on this same system, chamomile can amplify the sedative effect. This includes benzodiazepines, barbiturates, sleep medications, and some anti-anxiety drugs. The result can be excessive drowsiness, slowed breathing, or impaired coordination beyond what either substance would cause alone.
People Taking Certain Prescription Medications
Beyond blood thinners and sedatives, chamomile can interfere with how your liver processes a wide range of medications. Your liver uses a family of enzymes to break down drugs, and chamomile inhibits several of them. The most affected enzyme, CYP1A2, metabolizes dozens of common medications including some antidepressants, antipsychotics, and heart medications. Chamomile also shows some inhibitory activity against CYP3A4, which is involved in processing roughly half of all prescription drugs on the market.
When these enzymes are suppressed, medications stay in your bloodstream longer and at higher concentrations than intended. This effectively turns your normal dose into an overdose. The inhibition has been demonstrated in lab studies, and while the real-world effect of a single cup of tea may be modest, regular daily consumption could meaningfully shift how your body handles certain drugs. If you take prescription medications metabolized by the liver, it’s worth checking whether chamomile could alter their effectiveness.
People Managing Diabetes With Medication
Chamomile has a measurable blood sugar-lowering effect. A meta-analysis of randomized controlled trials found that chamomile consumption significantly reduced both fasting blood glucose and HbA1c (a marker of long-term blood sugar control). The effect on fasting blood sugar was statistically robust, with no significant variation between studies.
For someone managing type 2 diabetes with medication, this creates a compounding effect. Your diabetes medication is already calibrated to lower blood sugar by a certain amount. Adding chamomile tea on top of that could push your levels too low, particularly if you drink it regularly. Symptoms of hypoglycemia include shakiness, confusion, sweating, and in severe cases, loss of consciousness. If you use insulin or oral blood sugar-lowering medications, regular chamomile consumption could require adjustments to your treatment that you wouldn’t anticipate on your own.