Chamomile

This is the strongest part of chamomile's file, and it's genuinely better than the herb's reputation suggests - so it's worth walking through what the researchers actually did.

The foundation study is Amsterdam and colleagues, published in the Journal of Clinical Psychopharmacology in 2009. The team enrolled 61 outpatients with mild to moderate generalized anxiety disorder and randomized 57 of them: 28 received a standardized pharmaceutical-grade chamomile extract, 29 received identical dummy capsules, for 8 weeks. Neither the participants nor the staff handing out the capsules knew who got which - that's what makes it double-blind, and it's the whole reason the result means anything, because anxiety is exactly the kind of symptom that improves when someone believes they're being helped. The main measure was the Hamilton Anxiety Rating Scale, a standard clinician-administered questionnaire. The chamomile group's total scores fell significantly further than placebo (P = 0.047). The authors' own conclusion was carefully worded: chamomile "may have modest anxiolytic activity," and future studies were needed to replicate it. Note how close that P-value sits to the 0.05 threshold - this was a real result, but not a dramatic one.

The same research group then ran the much larger follow-up, published by Mao and colleagues in Phytomedicine in 2016. This one was built differently and is the more informative study. Between 2010 and 2015 they enrolled 179 outpatients with moderate-to-severe GAD. Everyone first took chamomile openly for 12 weeks at 1500 mg per day of pharmaceutical-grade extract - three 500 mg capsules daily. Of those, 93 responded well enough to continue, and only those responders were then randomized: 46 stayed on chamomile for another 26 weeks, 47 were quietly switched to placebo. The question was whether the people switched to placebo would relapse faster. And here's the honest result: they did relapse more often (25.5% vs 15.2%) and sooner (mean 6.3 weeks vs 11.4 weeks), but the difference did not reach statistical significance (hazard ratio 0.52, P = 0.16). The primary outcome, in other words, was negative. What did reach significance was that people who stayed on chamomile maintained meaningfully lower anxiety symptoms throughout follow-up (P = 0.0032), along with small reductions in body weight and mean arterial blood pressure. Adverse events were low and similar in both groups. The authors were candid that their sample was too small and the placebo group relapsed less than expected, which is why the headline finding fell short.

Zooming out, the 2019 systematic review and meta-analysis by Hieu and colleagues in Phytotherapy Research pooled 12 randomized and quasi-randomized trials. For diagnosed GAD it found significant improvement in Hamilton Anxiety scores at both 2 weeks and 4 weeks - though the absolute differences were small (around 1.4 to 1.8 points). Tellingly, when the same reviewers pooled three trials of ordinary situational "state" anxiety in people without a diagnosis, they found no difference from placebo at all.

So the fair summary is narrower than the internet's version: for people with persistent, diagnosable generalized anxiety, taking a concentrated standardized extract for weeks under supervision, chamomile produced small but genuine and repeatable improvements. For a healthy person feeling nervous before a presentation, the pooled evidence shows nothing. And none of this is a Health Canada permitted claim - the monograph allows traditional calmative wording only, and none of it is a reason to change or stop prescribed treatment.

"Chamomile makes you sleepy" is probably the most widely believed thing about this plant, so it deserves a precise answer rather than a comfortable one. The evidence splits cleanly in two, and the split is the whole story.

On general sleep quality, the picture is positive. The 2019 Hieu meta-analysis in Phytotherapy Research pooled six randomized trials measuring sleep quality and found a significant improvement with chamomile (standardized mean difference -0.73, P < 0.005) - a moderate effect by the usual conventions. A representative individual trial is Adib-Hajbaghery and Mousavi, published in Complementary Therapies in Medicine in 2017: 60 residents aged 60 and over at a nursing home in Iran were randomly assigned to either 200 mg chamomile extract capsules twice daily or matching wheat-flour capsules for 28 days, with sleep measured by the Pittsburgh Sleep Quality Index. Sleep quality was poor in both groups at baseline and significantly better in the chamomile group afterwards. It's a real result, but note the limitations the authors themselves worked within: single-blind rather than double-blind, 60 people, one facility.

A second example is Chang and Chen's trial in the Journal of Advanced Nursing in 2016, which recruited 80 Taiwanese postnatal women with poor sleep quality and assigned them to drink chamomile tea or not. The chamomile group scored significantly better on physical-symptom-related sleep inefficiency and on depression symptoms. But here's the finding that gets left out of the summaries: at the four-week follow-up, the two groups were indistinguishable again. Whatever chamomile was doing, it didn't persist after the intervention stopped.

Now the other half, and it's the part that should temper expectations. When researchers studied people with actual diagnosed insomnia rather than general poor sleep, chamomile did not perform. Zick and colleagues at the University of Michigan ran a randomized, double-blind, placebo-controlled pilot published in BMC Complementary and Alternative Medicine in 2011: 34 adults aged 18 to 65 with DSM-IV primary insomnia lasting at least six months took 270 mg of chamomile twice daily or placebo for 28 days, keeping sleep diaries. There were no significant differences between groups on any sleep diary measure - not total sleep time, not sleep efficiency, not how long it took to fall asleep, not night-time awakenings, not sleep quality. Chamomile showed a modest, non-significant edge on daytime functioning and fatigue. Total sleep time actually trended in placebo's favour. NCCIH's own assessment says exactly this: the one insomnia study in the 2019 review found no benefit.

How to reconcile these? The most honest reading is that chamomile doesn't work as a sedative - it isn't making you sleep by pressing a chemical off-switch. Where people already sleep badly because they're tense or unsettled, easing that seems to make nights feel better. Where insomnia is an entrenched clinical disorder, a mild herb doesn't touch it. Health Canada's monograph reflects this nuance carefully: it permits "traditionally used in Herbal Medicine to help relieve restlessness and/or nervousness (which helps to promote sleep)" - restlessness first, sleep as a consequence. That ordering is not accidental.

If the anxiety research is chamomile's most interesting file, the digestive use is its most durable one - and the two have very different kinds of evidence behind them.

Health Canada's monograph for German chamomile flower permits two digestive statements. The first, "Used in Herbal Medicine to help relieve inflammatory conditions of the gastrointestinal tract," is cited to the Expanded Commission E Monographs and the British Herbal Compendium. The second, "(Traditionally) used in Herbal Medicine to help relieve mild digestive upset (such as dyspepsia, flatulence, bloating and belching)," draws on a longer chain of sources running back through ESCOP and Mills and Bone to the American Eclectic physicians of the late 1800s and early 1900s. That's the specific, permitted, on-label language in Canada, and the parenthetical "traditionally" is doing real work: it signals that the authority here is centuries of documented use, not a modern trial.

The mechanism is unglamorous and well accepted. Chamomile acts as a carminative and antispasmodic - it relaxes the smooth muscle of the gut wall, which relieves cramping and allows trapped gas to move rather than distend. Laboratory work adds anti-inflammatory activity: chamomile extract has been described as inhibiting COX-2 enzyme activity, and an aqueous extract protected against ethanol-induced gastric ulceration in rats by raising glutathione levels. These are animal and in-vitro findings, so treat them as explaining the traditional use rather than proving a clinical one.

Where the modern evidence is genuinely thin is chamomile on its own. NCCIH is direct about this: combination products containing chamomile plus other herbs have shown some benefit for diarrhoea in children and for infant colic, but chamomile alone has not been shown to help those conditions. That distinction matters. A great deal of the digestive research uses multi-herb European preparations in which chamomile is one component among several - you cannot pull chamomile's individual contribution out of those results. The Health Canada monograph itself lists a functional dyspepsia trial of a herbal combination among its reviewed references rather than its cited ones.

One interesting adjacent finding, sitting outside the digestive claim but worth knowing: a trial reported in the Journal of Endocrinological Investigation found chamomile tea had positive effects on glycemic control in people with type 2 diabetes. That is not a permitted claim, not a reason to use chamomile for blood sugar, and not something to act on without your practitioner - but it's a reminder that a mild herb is still doing something measurable.

So: the digestive use is graded as traditional not because it's dubious, but because that's honestly what supports it - a very long, very consistent, well-documented history of use, formally recognised by Health Canada, with plausible mechanism and modest modern corroboration. For occasional bloating or an unsettled stomach after eating, it is the most defensible reason to reach for chamomile.

Chamomile has been applied to skin and swilled around mouths for as long as it's been drunk, and there is a modest but real modern research effort here - mostly in cancer supportive care, where inflamed mouths and irritated skin are common problems.

On oral mucositis - the painful mouth inflammation caused by chemotherapy and radiation - chamomile mouthrinses have been studied repeatedly since the 1990s, starting with a prospective evaluation of a chamomile mouthwash for 5-FU-induced mucositis published in Cancer in 1996. Memorial Sloan Kettering's assessment of the accumulated literature, including two later systematic reviews, is that the preliminary data on whether these products reduce or prevent mucositis are mixed and that additional studies are needed. NCCIH's phrasing is gentler but points the same way: small studies suggest chamomile mouthwashes might prevent or treat swelling or irritation in the mouth resulting from radiation therapy, chemotherapy or stem cell transplantation. "Might," "small," and "mixed" are the operative words - this is a legitimate area of investigation, not a settled finding.

On skin, there are a few individually interesting controlled trials. In one, a chamomile compress was compared against 1% hydrocortisone ointment for peristomal skin lesions in colostomy patients and was reported as effective and superior to the hydrocortisone - a striking result from a single small study that has not, to our knowledge, been replicated at scale. In another, a preliminary clinical trial compared a chamomile gel against urea cream for preventing acute radiation dermatitis in head and neck cancer patients, with some suggestion of benefit. Both are small, both are early, and neither establishes a general skin claim.

Two other topical or near-topical findings round out the picture, and both should be read as single studies rather than conclusions: a topical chamomile oleogel produced pain relief in a randomized double-blind crossover study in migraine without aura, and a chamomile extract spray was studied for prevention of post-operative sore throat.

The honest grading here is preliminary, and there are three reasons. The trials are small. Several use chamomile as part of a formulation rather than alone. And the results are inconsistent enough that reviewers keep landing on "mixed" rather than "effective."

Two practical notes. First, Health Canada's oral monograph - the one this page is built on - covers swallowing chamomile, not applying it. Topical chamomile products fall under different regulatory territory entirely. Second, and more important: the allergy caution is arguably sharper for topical use than oral. Contact dermatitis from chamomile is documented, chamomile-derived bisabolol has been implicated in reactions to skincare products, and NCCIH specifically warns that chamomile used near the eyes might cause eye irritation. If you are in the ragweed and daisy allergy group, chamomile on your skin is at least as much of a question as chamomile in your cup.

This claim exists because the Pennsylvania research group noticed something in their anxiety trials and followed it up honestly. It's worth including precisely because it shows what early-stage evidence looks like before anyone should act on it.

The starting point was an exploratory study by Amsterdam and colleagues, published in Alternative Therapies in Health and Medicine in 2012, asking whether chamomile might have antidepressant activity in anxious, depressed people. "Exploratory" is the researchers' own word, and it should be taken at face value: this was a look at data to generate a hypothesis, not a trial designed to test one.

The more substantial follow-up came in the Journal of Alternative and Complementary Medicine in 2020, again from Amsterdam, Li, Xie and Mao, titled - note the careful hedging in the researchers' own title - "Putative Antidepressant Effect of Chamomile Oral Extract in Subjects with Comorbid Generalized Anxiety Disorder and Depression." It drew on participants from the long-term GAD programme described in the anxiety claim above. The signal was a reduction in depressive symptoms in people who had both conditions. NCCIH's summary of this work is appropriately restrained: some preliminary studies suggest a chamomile dietary supplement might be helpful for generalized anxiety disorder and associated depression.

There are three limitations that matter enormously here, and none of them are technicalities. First, every participant had generalized anxiety disorder - this was never a study of depression on its own, so it says nothing about chamomile for someone with depression and no anxiety. Second, when you treat anxiety successfully, mood commonly improves as a consequence; disentangling a genuine antidepressant effect from that knock-on is exactly what these studies could not do. Third, this is essentially one research group analysing overlapping participant pools. Independent replication by other teams is the thing that would move this out of "preliminary," and it hasn't happened.

A related thread worth one line: an exploratory study by Keefe and colleagues in the Journal of Psychiatric Research in 2018 looked at salivary cortisol changes during chamomile therapy for moderate-to-severe GAD, and MSK notes chamomile may improve biological markers of stress in people with chronic anxiety. Interesting as supporting biology; not a clinical outcome.

We are flagging this claim as preliminary and stopping there deliberately. Health Canada grants chamomile no mood or depression claim of any kind - the monograph permits digestive and traditional calmative wording only. Nothing here is a reason to delay care, and if you are dealing with low mood, chamomile is not the intervention that will address it. We include this section because a complete picture of the research includes the parts that are only half-built.

One further safety note that belongs with any mood discussion: NCCIH observes that chamomile might have some of the same effects as estrogen, that preliminary work suggests it could reduce the effect of birth control pills, and that interactions with sedatives are theoretically plausible. If you take psychiatric medication of any kind, this is a conversation for your prescriber before it is a purchase.