Fennel - Sweet

Fennel is a simple herb with a surprisingly strict set of rules in Australia. These are the questions our naturopaths ask in store to check it suits you.

A good fit if

• You're an adult who gets wind and bloating after meals and you'd like to try the traditional seed tea
• You're happy with a short course, as European guidance limits use to 2 weeks
• You want a caffeine-free tea after dinner and you know the cautions below don't apply to you
• You'd like to try an extract for period pain and you understand the evidence is mixed

Check with us first if

• You're on hormone therapy or have a hormone-sensitive condition. Fennel has been studied as a plant compound with oestrogen-like activity, so talk it through with a practitioner.
• You use a contraceptive injection. In one trial, fennel brought back bleeding in women whose periods had stopped on it, which changes how that method behaves.
• You're allergic to daisies, ragweed or chrysanthemums. There's a known risk of cross-reaction within that plant family.
• You take any regular medicine. We don't have information on fennel interactions, and that's a gap, not a guarantee it's safe.
• You're thinking of fennel for menopause symptoms. The dose studied was 200 mg a day of an extract, and most products aren't that kind of preparation.
• If you take prescription medicine, check with your doctor, pharmacist or our naturopaths before you start.

• Dried sweet fennel seed and tea (Schedule 1 item 2189 FENNEL SWEET SEED DRY). Best known for: The milder variety, and what's in most fennel teas and kitchen jars. Absorption: Hot water carries some of the seed's oil into the cup, and more if the seed is freshly crushed. Typical use: European tradition uses 1.5 g in 250 ml of boiling water, three times a day (4.5 g daily), for no more than 2 weeks.
• Dried bitter fennel seed (Schedule 1 item 2186 FENNEL BITTER SEED DRY). Best known for: The stronger-tasting traditional medicinal variety, listed as a separate ingredient. Absorption: Brewed the same way as sweet fennel. We hold no data comparing absorption. Typical use: The European draft monograph describes 1.5 to 2.5 g of freshly crushed fruit in 250 ml of boiling water, three times a day.
• Fennel seed extract capsules. Best known for: The form used in nearly every clinical trial, for period pain and menopause. Absorption: Strength varies widely between products, so the label weight doesn't tell you the dose. Typical use: The best menopause trial used 200 mg of extract a day for 8 weeks. A 1 g seed powder capsule isn't the same preparation.
• Fennel essential oil (Schedule 1 item 2188 FENNEL OIL). Best known for: A concentrated oil, which must contain methyl chavicol. Absorption: Contains the oil at far higher strength than tea or seed. Typical use: Capped in Australia at 150 mg of oil a day, with container and flow-insert rules. Not something to choose for yourself.

Reference values. There isn't one. Fennel is a herb, not a nutrient, so there's no recommended daily amount and no such thing as a deficiency.

Typical supplemental range. Most fennel on Australian shelves is tea and seed sold as food, plus seed powder capsules and digestive herb blends. None of them are standardised. European traditional guidance for sweet fennel tea is 1.5 g of seed in 250 ml of boiling water, three times a day, which comes to 4.5 g a day. The trials used something different: the best menopause trial used 200 mg a day of a concentrated extract for 8 weeks, and you can't match that by weighing out seed powder capsules.

Upper level. Only fennel oil has an Australian limit: "The maximum daily dose must provide no more than 150 mg of fennel oil." Dried seed has no daily limit in Australia's rules. That doesn't mean unlimited amounts are fine, because European guidance says your intake of estragole from herbal medicines should be kept as low as possible.

Worth knowing. European guidance says "Not to be taken for more than 2 weeks." If your symptoms are still there after that, see a health professional rather than keep going. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Fennel bulb, the vegetable: an ordinary food, not a medicine ingredient. No verified composition figures held, so we won't publish one
• Fennel seed, the kitchen spice: sold in supermarkets as a spice. Same plant part as the teas and capsules, regulated as food
• Fennel tea sold as a food: the most common way Australians buy fennel. No per-cup figure exists in our sources

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• Pregnant, or likely to become pregnant. All oral fennel items must carry an Australian label warning. A 2017 review notes fennel can shorten pregnancy (gestational age). Don't take it.
• Breastfeeding. All oral fennel items must carry the warning 'Do not use while breastfeeding.' Cochrane rates the milk-supply evidence low to very low certainty. Don't take it.
• Children under 12, including babies with colic. Compulsory warning: 'Use in children under 12 years is not recommended'. The EMA sets a stricter estragole limit for children. Don't give it.
• Allergy to the Apiaceae family (aniseed, caraway, celery, coriander, dill, fennel) or to anethole. The EMA says not to use it. Don't take it.
• Mugwort pollen allergy. The EMA says not to use sweet fennel fruit. Don't take it.
• Daisy family (Asteraceae or Compositae) allergy. The EMA notes a risk of cross-reaction. Check with your doctor first.
• Hormone therapy or hormone-sensitive conditions. Fennel has been studied as a plant oestrogen. Check with your doctor first.
• Depot medroxyprogesterone acetate (the contraceptive injection). Fennel caused menstrual bleeding in a trial in this group. Check with your doctor first.
• Any regular medicine. We hold no data on fennel drug interactions, and that's a gap, not reassurance. Check with your doctor or pharmacist first.
• Fennel oil. Capped at 150 mg a day. Not something to choose for yourself.
• How long you take it. EMA monographs say no more than 2 weeks, and estragole intake should be kept as low as possible.
• If you take prescription medicines, check with your doctor, pharmacist or one of our naturopaths before you start.