The rhizome is candied and made into a sweetmeat[2, 4, 13, 55, 62, 115, 183]. It can be peeled and washed to remove the bitterness and then eaten raw like a fruit[106, 179]. It makes a palatable vegetable when roasted[192] and can also be used as a flavouring[61]. Rich in starch, the root contains about 1% of an essential oil that is used as a food flavouring[1, 13, 57]. The root also contains a bitter glycoside[179]. Some caution is advised, see the notes above on toxicity. The dried and powdered rhizome has a spicy flavour and is used as a substitute for ginger, cinnamon and nutmeg[4, 55, 142, 177, 183]. A pinch of the powdered rhizome is used as a flovouring in tea[272]. The young and tender inflorescence is often eaten by children for its sweetness[4]. Young leaves - cooked[55]. The fresh leaves contain 0.078% oxalic acid[240]. The leaves can be used to flavour custards in the same way as vanilla pods[244]. The inner portion of young stems is eaten raw[62]. It makes a very palatable salad[183].

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.


Sweet flag has a very long history of medicinal use in many herbal traditions. It is widely employed in modern herbal medicine as an aromatic stimulant and mild tonic[4]. In Ayurveda it is highly valued as a rejuvenator for the brain and nervous system and as a remedy for digestive disorders[254]. However, some care should be taken in its use since some forms of the plant might be carcinogenic - see the notes above on toxicity for more information. The root is anodyne, aphrodisiac, aromatic, carminative, diaphoretic, emmenagogue, expectorant, febrifuge, hallucinogenic, hypotensive, sedative, stimulant, stomachic, mildly tonic and vermifuge[4, 7, 9, 21, 147, 165, 213, 240, 279]. It is used internally in the treatment of digestive complaints, bronchitis, sinusitis etc[238]. It is said to have wonderfully tonic powers of stimulating and normalizing the appetite. In small doses it reduces stomach acidity whilst larger doses increase stomach secretions[254] and it is, therefore, recommended in the treatment of anorexia nervosa[244]. However if the dose is too large it will cause nausea and vomiting[K]. Sweet flag is also used externally to treat skin eruptions, rheumatic pains and neuralgia[238]. An infusion of the root can bring about an abortion[213] whilst chewing the root alleviates toothache[213]. It is a folk remedy for arthritis, cancer, convulsions, diarrhoea, dyspepsia, epilepsy etc. Chewing the root is said to kill the taste for tobacco[218]. Roots 2 - 3 years old are used since older roots tend to become tough and hollow[4]. They are harvested in late autumn or early spring and are dried for later use[4]. The dry root loses 70% of its weight, but has an improved smell and taste[244]. It does, however, deteriorate if stored for too long[244]. Caution is advised on the use of this root, especially in the form of the distilled essential oil, since large doses can cause mild hallucinations[192]. See also the notes above on toxicity. A homeopathic remedy is made from the roots[9]. It is used in the treatment of flatulence, dyspepsia, anorexia and disorders of the gall bladder[9]. Bath oils containing calamus have caused redness of the skin (erythema) and dermatitis, particularly in hypersensitive individuals [301].

The leaves are used in basket making or woven into mats[169]. They have also been used as a thatch for roofs[4]. An essential oil from the rhizome is used in perfumery and as a food flavouring[1, 13, 57]. The oil is contained mainly in the outer skin of the root[245], it has a fragrance reminiscent of patchouli oil[192]. The fresh roots yield about 1.5 - 3.5% essential oil, dried roots about 0.8%[4, 240]. Some plants from Japan have yielded 5% essential oil[4]. The essential oil is also an insect repellent and insecticide[218, 272]. It is effective against houseflies[240]. When added to rice being stored in granaries it has significantly reduced loss caused by insect damage because the oil in the root has sterilized the male rice weevils[244]. An essential oil obtained from the leaves is used in perfumery and for making aromatic vinegars[245]. The leaves and the root have a refreshing scent of cinnamon[245]. All parts of plant can be dried and used to repel insects or to scent linen cupboards[8, 14, 61]. They can also be burnt as an incense[14], whilst the whole plant was formerly used as a strewing herb[4, 14, 115, 238]. The growing plant is said to repel mosquitoes[20, 201].

Special Uses