Does Star Anise Have Negative Side Effects?

December 25, 2025 •

3 min read

While Chinese star anise (Illicium verum) is a common culinary spice, its toxic counterpart, Japanese star anise (Illicium anisatum), has led to serious poisoning cases worldwide. A primary negative side effect of star anise is the risk of adulteration with this highly poisonous look-alike, which can cause severe health issues.

Quick Summary

This guide examines the health risks associated with star anise, focusing on poisoning from the toxic Japanese species and overdose symptoms from the Chinese variety. It covers specific side effects, at-risk populations, potential drug interactions, and crucial safety precautions.

Key Points

Contamination with Japanese Star Anise: The most dangerous risk is consuming toxic Japanese star anise (Illicium anisatum), which is often mistaken for the safe Chinese variety, leading to severe poisoning.
Neurotoxic Effects: Ingestion of the toxic species can cause severe neurological symptoms, including seizures, convulsions, irritability, and hallucinations, particularly in infants and children.
Gastrointestinal Distress: Both contamination and high-dose consumption of Chinese star anise can cause severe gastrointestinal issues like vomiting, nausea, and abdominal cramps.
High-Risk Populations: Infants, children, and pregnant or breast-feeding women should avoid star anise due to heightened toxicity risks and lack of safety data.
Potential Drug Interactions: Star anise can interact with medications, including blood thinners, blood sugar–lowering drugs, and hormone treatments.
Allergic Reactions: Though less common, allergic responses like rashes and swelling can occur, especially in those sensitive to related plants.
Dose-Dependent Toxicity: Even pure Chinese star anise can cause adverse effects if consumed in large quantities, especially when brewed as a strong tea.

The Primary Threat: Japanese Star Anise Contamination

The most significant negative side effect associated with star anise is the risk of contamination with Japanese star anise (Illicium anisatum), a different and highly toxic species. Chinese star anise (Illicium verum), which is used in cooking, and Japanese star anise are visually very similar, making them difficult to distinguish without chemical analysis. Japanese star anise contains potent neurotoxins like anisatin, which can cause severe neurological and gastrointestinal problems upon ingestion.

Poisoning incidents have occurred globally, particularly involving star anise tea. Health authorities, including the U.S. FDA, have warned against consuming star anise tea due to these contamination risks. Symptoms can include irritability, lethargy, seizures, severe vomiting, and abdominal cramps. Infants are particularly susceptible to these adverse effects, with many poisoning cases reported in children.

Adverse Effects of Overconsumption

Even pure Chinese star anise can cause negative side effects if consumed in excessive amounts. It contains compounds that can be toxic at high doses, such as veranisatin, which can cause neurological symptoms. Consuming large quantities, like multiple strong cups of tea, has resulted in giddiness, neurological issues, and severe gastrointestinal distress. This is a concern for those using star anise in medicinal preparations, where concentrations are often higher than in food.

Allergic Reactions and Drug Interactions

Star anise can also cause allergic reactions in some individuals, though this is less common. Symptoms may include rashes and swelling. People allergic to related plants like fennel or celery might have a higher risk. Additionally, star anise may interact with medications. Its components can have mild blood-thinning effects, which could be risky for those on anticoagulants. There's also potential for interaction with blood sugar medications, as studies suggest star anise extract can lower blood sugar.

Populations at Higher Risk

Caution with star anise is particularly important for certain groups:

Infants and Children: Due to documented cases of severe toxic effects, often linked to Japanese star anise contamination, star anise is generally not recommended for infants and young children.
Pregnant and Breast-feeding Individuals: The safety of star anise during pregnancy and breastfeeding is not well-established, and it is considered possibly unsafe in medicinal amounts. Avoiding use during these times is advised.
Individuals on Certain Medications: Those taking blood thinners, blood sugar–lowering medications, or hormone therapies should be cautious and consult a healthcare provider due to potential interactions.

Star Anise Species Comparison


Feature	Chinese Star Anise (Illicium verum)	Japanese Star Anise (Illicium anisatum)
Toxicity	Generally safe in small, culinary amounts. Higher doses or tea concentrations can still be toxic.	Highly toxic due to potent neurotoxins like anisatin.
Appearance	Visually very similar to Japanese star anise, with both having an 8-pointed star shape.	Visually very similar to the Chinese species, making it a dangerous look-alike.
Aroma	Sweet, strong, licorice-like aroma.	Weaker, more pungent, and medicinal scent.
Culinary Use	Common spice in Asian and other cuisines.	No culinary use; traditionally used as incense in Japan.
Primary Risk	Overconsumption or adulteration with the Japanese variety.	Accidental ingestion due to misidentification.

Conclusion

While pure Chinese star anise is generally safe in small culinary amounts, it does have potential negative side effects. The most significant risk is contamination with the highly toxic Japanese star anise, which can cause severe health issues. Even the Chinese variety can cause adverse effects if consumed in large quantities. Infants, children, pregnant women, and those on certain medications should be particularly careful. Safe sourcing from reputable suppliers and moderation are essential for safe use.

A Safe Sourcing and Usage Guide

Here are some practical tips for using star anise safely:

Verify the Source: Only purchase star anise from trusted suppliers who can guarantee it is pure Illicium verum.
Inspect Before Use: Visually check whole pods for irregularities. The toxic variety is sometimes described as smaller and less fragrant.
Use in Moderation: Stick to small culinary amounts. Avoid large doses, especially in teas or concentrated forms.
Avoid Risk Groups: Do not give star anise to infants, children, or pregnant/breastfeeding women.
Consult a Professional: If you have health conditions or take medications, consult a healthcare provider before using star anise.

For more information on differentiating star anise species and safe usage, consult reliable botanical and medical resources.

Frequently Asked Questions

The primary reason is the risk of contamination with toxic Japanese star anise, which looks almost identical to the safe Chinese star anise but contains potent neurotoxins that can cause poisoning.

Yes, particularly when the product is contaminated with Japanese star anise, which contains a neurotoxin called anisatin. Several cases of seizures, especially in infants, have been linked to consuming contaminated star anise tea.

Yes. Chinese star anise (Illicium verum) is safe for consumption in culinary amounts, while Japanese star anise (Illicium anisatum) is poisonous. They are difficult to distinguish visually but differ chemically.

Yes, adults can experience side effects from star anise, primarily through ingesting contaminated products or by consuming excessively high doses of the Chinese variety, which can lead to neurological or gastrointestinal symptoms.

Star anise should be avoided by infants, children, and pregnant or breast-feeding women due to the risk of toxicity and lack of safety information. Individuals on blood thinners or diabetes medication should also consult a doctor.

Symptoms of star anise poisoning can include vomiting, nausea, abdominal cramps, irritability, lethargy, and neurological symptoms like seizures and twitching.

Star anise tea is considered possibly unsafe because it is impossible to be certain that the star anise has not been contaminated with the toxic Japanese species. Health authorities have warned against consuming it due to reports of serious side effects.