Quick answer
A 2025 systematic review of 72 trials and 11 case reports found drowsiness and gastrointestinal complaints were the most common adverse events with chamomile, and that they were self-limiting and not serious. Across 10 trials with 2,896 people given chamomile, 65 events were reported. Ask your doctor if chamomile makes you drowsy.1,2
Key facts
- A 2025 systematic review found drowsiness and gastrointestinal complaints were the most common adverse events with chamomile, both self-limiting and not serious.1
- The review found 65 adverse events across 10 trials among 2,896 people given chamomile, and no adverse event data at all in 28 trials.1
- NCCIH says side effects are uncommon and may include nausea, dizziness and allergic reactions.2
- NCCIH says there are theoretical reasons chamomile might interact with sedatives.2
- Only one of the 10 sleep trials in a 2024 review checked the purity or strength of the chamomile it used.3
What did the systematic review of adverse events find?
The review searched three databases for human reports of adverse events with chamomile alone. It included 72 trials and 11 case reports. In the trials, 2,896 people received chamomile, and 65 adverse events were reported across 10 trials. The most common were gastrointestinal complaints and drowsiness, and both were self-limiting and not serious.1
Three limits shape how to read that. Incomplete reporting limited the review, 28 trials gave no adverse event data at all, and only 10 trials reported any events. Counting only what trials reported, the sources can tell us what is common among the few events recorded, not how often a given person will feel drowsy.1
What does NCCIH say?
NCCIH calls side effects of chamomile uncommon and names nausea and dizziness, along with allergic reactions. It does not list drowsiness among them, but it does say there are theoretical reasons to suspect chamomile might interact with other drugs, such as sedatives.2
Side effects are uncommon. Nausea and dizziness have been reported.2
What do trials of chamomile for sleep add?
Trials of chamomile for sleep give a second view, since a person taking it at night would expect to feel drowsy. A 2024 systematic review of 10 sleep trials found that only one checked the purity or strength of the chamomile it used, and that most recorded side effects only when people reported them. A 2019 review of 12 randomized trials found mild adverse events in only three of them. The longest trial gave chamomile for 12 weeks and then continued it for 26 more weeks in a randomized group, with side effect rates similar to placebo.3,4,5
Only one of the 10 sleep trials in a 2024 review checked the purity or strength of the chamomile it used, and most recorded side effects only when people reported them.3
The longest trial gave 1,500 mg of extract a day for 12 weeks, then continued it for 26 more weeks in a randomized group, with side effect rates similar to placebo.5
What about gas, reflux, constipation and other digestive effects?
The review's category of gastrointestinal complaints is broad, and its abstract does not break it down into gas, reflux, constipation or diarrhea. NCCIH names nausea. None of the sources we read tell us which digestive effects are more likely, so a person who notices a specific one is describing something the sources do not rank.1,2
Who should ask a doctor?
- Anyone taking a sedative, a sleeping medicine or any medicine that makes them sleepy should ask a pharmacist before adding chamomile.
- Anyone with a ragweed or daisy-family allergy should ask first, because allergic reactions are the more serious risk.2
- Anyone who feels drowsy during the day after using chamomile should tell a doctor, together with the product label.
Questions people ask
Is drowsiness from chamomile common?
It was among the most common events in a 2025 systematic review, which found 65 adverse events across 10 trials, all self-limiting and not serious. Many trials recorded no adverse event data.1
Does chamomile cause headaches, gas or diarrhea?
The review named gastrointestinal complaints without listing them, and NCCIH names nausea. The sources we read do not name headaches, gas or diarrhea as chamomile effects, which is not a finding either way.1,2
Does chamomile cause acid reflux or constipation?
The sources we read do not mention acid reflux or constipation. They describe gastrointestinal complaints in general terms. Ask your doctor if digestive symptoms follow chamomile.1
Does chamomile tea cause nightmares or contractions?
None of the sources we read report nightmares or uterine contractions as effects of chamomile. For pregnancy, see our page on chamomile during pregnancy, and ask your doctor.2
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Sources
- Ostovar M, Rezaee Z, Najibi SM, Hashempur MH. Chamomile: a systematic review of adverse events. Complement Ther Med. 2025;91:103192. Opened 2026-10-11.
- National Center for Complementary and Integrative Health. Chamomile. Bethesda (MD): National Institutes of Health. Last updated November 2024. Opened 2026-10-07.
- Kazemi A, Shojaei-Zarghani S, Eskandarzadeh P, Hashempur MH. Effects of chamomile (Matricaria chamomilla L.) on sleep: A systematic review and meta-analysis of clinical trials. Complement Ther Med. 2024;84:103071. Opened 2026-10-07.
- Hieu TH, Dibas M, Surya Dila KA, et al. Therapeutic efficacy and safety of chamomile for state anxiety, generalized anxiety disorder, insomnia, and sleep quality: a systematic review and meta-analysis of randomized trials and quasi-randomized trials. Phytother Res. 2019;33(6):1604-1615. Opened 2026-10-07.
- Mao JJ, Xie SX, Keefe JR, et al. Long-term chamomile (Matricaria chamomilla L.) treatment for generalized anxiety disorder: A randomized clinical trial. Phytomedicine. 2016;23(14):1735-1742. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.