Chamomile: Traditional Use, Constituents and Evidence

A flower with a very long paper trail

My nan grew German chamomile along the back fence of her Stirling property, just off Mount Barker Road in the Adelaide Hills. She'd cut it in the early morning, spread it on a clean hessian cloth on the veranda, and then make tea from it for years afterwards. She never called it a medicine exactly. She just called it "useful." I find that framing , useful, but not overclaimed , genuinely useful myself when I read the research.

Chamomile is one of the most documented plants in the Western herbal tradition, which also means it is one of the most over-claimed. Separating what the constituent chemistry tells us from what traditional use suggests, and from what evidence actually supports, takes some patience. Let's have a go.

Taxonomy and traditional context

Two species dominate commercial use. Matricaria chamomilla L. (German or Hungarian chamomile) is the one most studied and most widely sold in Australia. Chamaemelum nobile (Roman chamomile) is chemically distinct and used somewhat differently in European traditions. Most of what follows concerns German chamomile unless specified.

The documented use of chamomile runs from ancient Egyptian writings through the Greek physician Dioscorides (roughly 50–70 CE) to the Anglo-Saxon herbal tradition. By the early modern period, dried chamomile flowerheads appeared in virtually every European domestic medicine chest. Its presence in the 1st-century De Materia Medica and in 19th-century herbals like Coffin's Botanic Guide to Health (1845) tells you this plant had enduring practical appeal across widely different cultural contexts. That kind of continuity doesn't confirm efficacy , but it does make it a reasonable subject for phytomedicine research.

Key constituents: what the chemistry shows

The dried flowerhead yields a fairly complex mixture. Understanding the main chemical classes matters because researchers often study isolated constituents, and that shapes what the evidence can and cannot tell us.

Flavonoids are arguably the most studied fraction. Apigenin is the dominant flavonoid in German chamomile and the one attracting the most mechanistic research. It's a flavone with demonstrated affinity for the benzodiazepine site of the GABA-A receptor in in vitro models; which is why it appears so often in the pharmacological literature. The caveat: receptor-binding assays in cell cultures are a very long way from clinical outcomes in people, and apigenin's oral bioavailability is low and affected considerably by gut metabolism. Luteolin and quercetin are also present in smaller quantities.

Terpenoids are another major fraction, primarily in the essential oil. The characteristic blue colour of freshly steam-distilled German chamomile oil comes from chamazulene, formed during distillation from matricine. Alpha-bisabolol (see our glossary entry on bisabolol) is a sesquiterpene alcohol considered one of the principal active constituents; it is present in meaningful concentrations in high-quality German chamomile but varies enormously between cultivars and harvest times. There's also a modest terpene profile including alpha-pinene (covered in our alpha-pinene entry) and smaller amounts of related volatiles.

Coumarins (including herniarin and umbelliferone), hydroxycinnamic acid derivatives, and polysaccharides are also present and contribute to what some researchers consider a whole-extract effect. Whether that represents something like an entourage effect, where constituents modulate each other's activity, is a genuinely interesting open question in phytomedicine broadly, but it's not resolved for chamomile specifically.

What standardisation means in practice

Commercial preparations differ enormously. Bulk dried flower, tea bags, tinctures, hydroethanolic extracts, and topical preparations will have quite different constituent profiles. A standardised extract specifies a guaranteed minimum of one marker compound (often apigenin) per dose, which at least gives researchers and consumers a reference point. An unstandardised tea from mixed-origin flowers gives you something chemically different with each batch; which is perfectly fine for a pleasant evening drink, but makes clinical research comparisons messy.

Under the Therapeutic Goods Administration's framework, complementary medicines in Australia that make therapeutic claims must be listed or registered on the Australian Register of Therapeutic Goods (ARTG). Listed medicines (AUST L number) require evidence of traditional use or low-level evidence of efficacy, and the TGA publishes its permitted indications list for chamomile. That list is more restricted than what you'll read on many overseas websites. Manufacturers supplying an unlisted product with unsubstantiated therapeutic claims risk regulatory action. Worth knowing if you're comparing Australian stock with imports.

The research landscape, and its real limits

Honest assessment: the human clinical trial base for chamomile is small, often underpowered, and heterogeneous in the extracts used. There are studies; they just don't yet add up to the kind of consistent evidence base that warrants strong clinical conclusions.

Most published human trials have examined outcomes in areas like sleep quality, gastrointestinal comfort, and mood, which aligns with traditional use, for what that's worth. But a 2019 systematic review published in Phytomedicine (Hieu et al.) noted significant variability in methodology across chamomile trials, small sample sizes, and inconsistent extract standardisation. That's a polite way of saying we can't pool the evidence cleanly. I'd argue the field has sometimes been too quick to extrapolate from in vitro mechanistic data to implied clinical benefit; a pattern common in botanical medicine more broadly.

The in vitro work on apigenin's GABA-A receptor affinity is genuinely interesting mechanistically. The same caveat that applies to much receptor pharmacology also applies here though: receptor binding in an isolated cell line doesn't account for the pharmacokinetics of getting a meaningful concentration to that receptor in an intact human being, through the gut barrier, first-pass metabolism in the liver, and plasma protein binding on the way. The gap between mechanism and outcome is real.

Topical preparations, creams and ointments containing chamomile extract or alpha-bisabolol, have a somewhat better-evidenced profile, partly because the pharmacokinetic hurdles are different and partly because there are more controlled studies. But even here, the effect sizes in published trials are modest.

Safety and Australian regulatory context

German chamomile is generally regarded as low-risk at typical culinary and tea-dose levels. The most clinically relevant safety flag is cross-reactivity in people with Asteraceae (daisy family) plant allergies; ragweed, chrysanthemum, daisy and marigold sensitivities are the common ones, and chamomile shares relevant allergens. Contact dermatitis and, in rare cases, anaphylaxis have been reported, particularly with concentrated extracts. This isn't rare enough to ignore in the allergy context.

Drug interactions: apigenin and other chamomile constituents show CYP450 enzyme inhibition in in vitro models, particularly CYP1A2 and CYP3A4. The clinical significance at realistic consumption levels is unclear, but people taking narrow therapeutic index drugs metabolised by those pathways, warfarin being the most commonly cited example, are generally advised to discuss chamomile supplement use with their prescriber.

There is no Australian import restriction on chamomile comparable to, say, the controls on kava (Piper methysticum), which is subject to specific import conditions under the Customs (Prohibited Imports) Regulations 1956 and ongoing monitoring by the TGA. Chamomile sits in the general low-risk complementary ingredient category, but the ARTG listing requirements and permitted indications still apply to any finished product making therapeutic claims.

Why traditional use still matters; carefully

I'll admit I spent years being a bit dismissive of traditional use as evidence. I've come around on this, mostly because good ethnobotanical documentation actually tells you something about real-world safety over long time horizons, in ways that a six-week RCT simply can't. Chamomile's multi-millennia, multi-culture use record, across widely different populations and preparation methods, does provide a reasonable safety signal. It does not, however, tell you the extract is doing what a modern therapeutic claim says it's doing at a specific dose.

That distinction, between traditional documentation and contemporary therapeutic claim; is the one worth holding onto when you're reading a product label or a wellness website. They're different things.

And on that note: my nan's chamomile is still growing in that Stirling garden, now tended by my cousin. I cut some last spring. The smell hit me before I reached the fence.

Sources

• Listed medicines evidence guidelines, Therapeutic Goods Administration (TGA)
• Chamomile: A herbal medicine of the past with bright future, Molecular Medicine Reports, NCBI/NLM
• Therapeutic efficacy and safety of chamomile for state anxiety, generalized anxiety disorder, insomnia and sleep quality; Phytomedicine, NCBI/NLM
• Permissible indications determination for listed medicines, TGA

, Naomi Ellison, Botanical & phytomedicine writer