The Flu Drug Tamiflu Starts With a Compound in Your Spice Rack — and There’s a Safety Warning That Comes With It
Bunga Lawang (Illicium verum) is the primary global source of shikimic acid — the starting material for oseltamivir (Tamiflu). It is also involved in one of the most serious species-confusion poisoning risks in the spice world. Both facts belong in the same article.
Chinese star anise (Illicium verum, the edible cooking spice) has a near-identical twin: Japanese star anise (Illicium anisatum), an ornamental plant containing anisatin — a neurotoxin that causes seizures, vomiting, hyperreflexia, and potentially fatal neurological damage. The two species are extremely difficult to tell apart by visual inspection, and mislabelled or mixed star anise has entered commercial supply chains repeatedly. Multiple serious poisoning cases — including infant deaths — have been documented.
Do not give star anise tea to infants under any circumstances. For baby colic, use fennel seed water instead — it has direct RCT evidence and no toxic lookalike species. Buy star anise only from a supplier who specifically guarantees Illicium verum.
Here’s the part that sounds made up but isn’t: during the 2009 H1N1 pandemic, roughly 90% of the world’s pharmaceutical shikimic acid — the essential starting material for Tamiflu — came from a single spice most people only associate with bak kut teh and biryani. That same eight-pointed pod has flavoured Chinese five-spice for centuries, carried its own antiviral chemistry long before any drug company noticed, and has a near-identical toxic twin that has quietly caused infant deaths through mistaken identity. It is, at once, one of the most pharmacologically important spices on Earth and one of the few where getting the species wrong can genuinely kill someone. Both of those facts are true, and you need both before you brew a single cup.
Two terms carry this article — worth defining plainly before we lean on them.
Shikimic acid is a plant compound that serves as the essential starting material chemists use to synthesise oseltamivir, the antiviral drug sold as Tamiflu. Star anise is the world’s primary commercial source of it.
Anethole is the aromatic compound responsible for star anise’s sweet liquorice scent — the same compound found in fennel. It has documented anti-inflammatory, antimicrobial, and mild smooth-muscle-relaxant activity.
Five Things Everyone Gets Wrong About Star Anise
“Star anise tea cures flu like Tamiflu does”
It contains the raw material Tamiflu is synthesised from — not the finished pharmaceutical. Real activity, different thing.
“All star anise is the same”
A near-identical, genuinely toxic species exists, and it has caused documented poisonings, including in infants.
“It’s natural, so it’s safe for babies”
This is precisely the reasoning that has led to real infant harm. Use fennel for colic instead.
“It’s just a five-spice flavour note”
Shikimic acid and anethole are doing genuine, documented anti-inflammatory and antiviral chemistry with every bowl of bak kut teh.
“It works for period pain exactly like fennel does”
Same compound, weaker direct evidence — the mechanism carries over, the clinical trials mostly don’t.
In the Malaysian Kitchen
Bunga lawang is one of the most recognisable spices on a Malaysian table — the eight-pointed star floating in a pot of biryani, the aromatic anchor of bak kut teh, a component of both Malay rempah blends and Chinese five-spice powder. In the culinary quantities used in these dishes, it is safe and it is delivering documented pharmacological activity — shikimic acid, anethole, and flavonoid anti-inflammatory compounds — with every meal.
Bak kut teh in particular pairs star anise with cloves, cinnamon, garlic, and pepper — a combination of independently anti-inflammatory, antimicrobial, and antioxidant spices assembled long before anyone could name the compounds responsible. This is multi-target food pharmacology hiding inside comfort food.
Of everything in this series, star anise is the one that keeps me most honest. It is genuinely remarkable — a global antiviral drug supply chain running through a spice most people only associate with bak kut teh — and it is also the one spice in the kitchen where getting the species wrong has killed a child. Both of those things are true at the same time, and neither one cancels the other out. That tension is the whole point of writing these articles properly instead of picking a side.
The Science
Primary Global Source
Star anise provides roughly 3–7% shikimic acid by dry weight. During the 2009 H1N1 pandemic, approximately 90% of the world’s pharmaceutical shikimic acid supply came from Chinese star anise.
Direct Antiviral Activity
Shikimic acid itself demonstrates measurable antiviral activity against influenza A and B in laboratory studies, independent of its role as a drug-synthesis precursor.
Shared Compound With Fennel
Anethole carries anti-inflammatory, antimicrobial, and smooth-muscle-relaxant activity across both fennel and star anise, through the same mechanism.
Documented Neurotoxicity Risk
Japanese star anise (Illicium anisatum) contains anisatin, which causes seizures, vomiting, hyperreflexia, and potentially fatal neurological damage — and is visually near-indistinguishable from the edible species when dried.
Myth-Busting Star Anise
“Star anise tea cures the flu — it contains the same thing as Tamiflu.”
Star anise contains shikimic acid, which pharmaceutical synthesis converts into oseltamivir (Tamiflu), and shikimic acid itself has documented antiviral activity. But “contains the same thing as Tamiflu” conflates a raw material with a finished, multi-step-synthesised pharmaceutical with targeted antiviral selectivity. Star anise tea delivers real, meaningful antiviral chemistry — it is not equivalent to the drug.
“All star anise sold in shops is safe — it’s natural.”
Japanese star anise (Illicium anisatum) is a real, documented, toxic lookalike that has repeatedly entered commercial spice supply chains through mislabelling or mixing. It contains anisatin, a neurotoxin. “Natural” describes an origin, not a safety guarantee — this is one of the clearest cases in the entire spice cabinet where that distinction matters.
“Star anise tea is a gentle, natural remedy for baby colic.”
Regulatory authorities in France, the United States, and Australia specifically advise against giving star anise tea to infants, following documented poisoning cases linked to species confusion — including infant deaths. Fennel seed water has direct RCT evidence for colic and carries no equivalent toxic-lookalike risk. This is the one substitution in this whole series that is not optional.
“Star anise tea eases menstrual cramps as reliably as fennel tea.”
Anethole’s smooth-muscle-relaxant and mild phytoestrogenic activity provide the same mechanistic basis documented for fennel. But star anise itself lacks fennel’s directly comparative clinical trial evidence — including the fennel-vs-ibuprofen dysmenorrhoea RCT. The mechanism carries over through the shared compound; the dedicated clinical evidence largely does not.
Petua Corner
Star anise tea for flu and cough. Shikimic acid and anethole both show real antiviral and anti-inflammatory activity — a pharmacologically rational supportive measure, not a Tamiflu replacement.
Star anise for post-meal digestion (the bak kut teh logic). Anethole’s carminative and antimicrobial activity — the same mechanism documented for fennel, in a more concentrated single pod.
Star anise tea for sleep. Anethole shows mild sedative-adjacent activity in preliminary studies, but dedicated human evidence for star anise and sleep specifically is limited.
Star anise tea for baby colic. The species-confusion poisoning risk overrides any folk mechanism here. Use fennel seed water instead.
Star anise tea for menstrual discomfort. Mechanism shared with fennel via anethole; the dedicated clinical evidence base for star anise specifically is thinner.
Honest Limitations
- Much of the clinical evidence attributed to star anise’s mechanisms is borrowed from studies on isolated shikimic acid or anethole (also found in fennel), rather than from trials on star anise tea or extract itself.
- There is no dedicated large-scale human RCT on star anise tea for flu, cough, sleep, or menstrual symptoms.
- A meaningful share of the available safety literature focuses on avoiding harm from species confusion rather than characterising benefit — which is itself an important part of the honest picture.
- Shikimic acid’s presence in star anise does not make the raw spice pharmaceutically equivalent to Tamiflu; the synthesis process changes both the molecule and its selectivity.
⚠ Caution
Never give star anise tea to infants or young children. The species-confusion risk with toxic Japanese star anise is real and has caused documented serious poisonings and deaths. Use fennel seed water for infant colic instead.
Buy star anise only from a supplier who specifically verifies Illicium verum. If a batch smells unusually bitter or looks visually inconsistent, do not use it.
Those on anticoagulant medication or with a known seizure disorder should consult a doctor before therapeutic-dose use of star anise preparations, given shikimic acid’s biological activity and the cross-contamination risk with anisatin. Normal culinary use in five-spice or bak kut teh from a trusted vendor is standard and safe.
References
- Studies on shikimic acid content and extraction from Illicium verum, and its role as the industrial precursor for oseltamivir (Tamiflu) synthesis.
- Laboratory studies on shikimic acid’s direct antiviral activity against influenza A and B.
- Studies on anethole’s anti-inflammatory, antimicrobial, and smooth-muscle-relaxant activity, shared between star anise and fennel.
- Case reports and regulatory guidance (France, USA, Australia) on Illicium anisatum (Japanese star anise) poisoning, including documented paediatric cases.
- Toxicology studies on anisatin’s neurotoxic mechanism.