Calamus (Sweet Flag) Essential Oil: Why Aromatherapists Hardly Work with It

In short: Oil from the rhizomes of sweet flag (calamus) may contain up to 85–95 % beta-asarone, a substance that is genotoxic and carcinogenic in rodents. Do not use it on the skin, in the bath or internally. If at all, then exceptionally 1 drop in a blend in an oil burner in a ventilated room.

In aromatherapy calamus has the reputation of a mysterious, "meditative" scent from the Indian tradition. It really does smell interesting: warm, spicy and earthy. But with this oil it is more important to know what it contains than how it smells.

We say this openly: most aromatherapists do not work with calamus and do not recommend it. If you already have calamus oil at home or are thinking about it, here is why that is so and how to handle it so that it does you no harm.

Three Forms of Sweet Flag and One Number That Matters

Sweet flag exists in several forms that differ in the number of chromosome sets (ploidy). On this depends how much beta-asarone its oil contains. The European Medicines Agency (EMA) gives these values:

Our oil comes from India. Until the supplier provides an analysis with the asarone content, it is sensible to assume the worse case, that is an oil in which beta-asarone makes up the majority.

What the Authorities Say About Beta-Asarone

• EMA (2005): alpha- and beta-asarone are genotoxic and cause liver tumours in rodents. Their content in herbal preparations should be as low as possible and diploid forms without asarone should be preferred. The EMA also mentions an anticoagulant effect of beta-asarone in mice and rats.
• IFRA (standard for asarone): asarone must not be used as a fragrance ingredient. Natural extracts, for example calamus oil, are acceptable only if asarone in the finished product does not exceed 0.01 % (100 ppm).
• EU, flavourings regulation 1334/2008: beta-asarone must not be added to food as such and tetraploid sweet flag must not be used to make food flavourings. In alcoholic drinks at most 1 mg/kg of beta-asarone is permitted.
• Specialist literature: a review of toxicological data from 2021 describes for asarones cardiotoxicity, hepatotoxicity, reproductive toxicity, mutagenicity and carcinogenicity, with varying reliability of evidence.

What does "genotoxic" mean? The substance damages the hereditary information of cells, DNA. For such substances a safe dose below which the risk disappears completely is usually not set, and the authorities therefore choose the principle of the lowest possible exposure. This is the main difference from oils that "only" irritate the skin: there it is enough to dilute the oil more, with asarone dilution only reduces the risk. That is why the EMA recommends giving preference to forms of sweet flag that contain no asarone at all.

What This Means for Home Use

When an oil contains around 90 % asarone, the IFRA limit of 0.01 % asarone corresponds to roughly 1 drop of oil per half a litre of product. Such a dilution makes no sense in home cosmetics. Clear rules follow from this:

1. Do not use calamus on the skin, not even diluted in a carrier oil, ointment or balm.
2. Do not put it in the bath.
3. Never take it internally, do not add it to food, drinks or home liqueurs.
4. If you want to try it, then only exceptionally 1 drop in a blend with other oils in an oil burner, briefly and in a ventilated room, not in the bedroom.
5. Keep the bottle locked away and out of the reach of children.

Why Tradition Knew It and Why It Is Being Moved Away From Today

According to the EMA, the rhizome of sweet flag was used in folk medicine all over the world, in Europe also as a bitter ingredient in liqueurs and in India in Ayurveda. We write about the traditional use of oils in India in the article Indian aromatherapy. The traditional use, however, concerned the dried rhizome and its infusions, not a concentrated essential oil. Knowledge about the genotoxicity of asarones came only in recent decades and it is precisely this that led to the current restrictions.

An Earthy Scent Without Asarone: What to Replace Calamus With

If you are drawn to a deep, spicy scent for moments of calm, you can create the same atmosphere with safer oils:

• Meditation (diffuser, 100 ml): 2 drops of frankincense, 1 drop of myrrh, 1 drop of Himalayan cedar.
• Warm spicy evening (diffuser, 100 ml): 2 drops of Himalayan cedar, 1 drop of ginger, 2 drops of orange.
• Earthy oil burner: 1 drop of angelica, 2 drops of frankincense.

How to compose scents is described in the article how to combine essential oils, the general safety principles are summarised in safe use of essential oils.

Who Must Avoid Calamus Entirely

• pregnant and breastfeeding women, even in a diffuser,
• children of all age groups (see essential oils and children),
• people with liver disease and people taking blood-thinning medicines,
• pets, especially cats: do not use it at all in a room with an animal.

Frequently Asked Questions

Is calamus oil poisonous?

It contains beta-asarone, which is genotoxic and carcinogenic in rodents. In Indian oil it may make up as much as 85–95 %. That is why calamus is not used on the skin or internally, and into the air only exceptionally.

Can I use calamus in a massage oil?

No. The IFRA limit for asarone (0.01 % in the finished product) corresponds for Indian oil to roughly 1 drop per half a litre, which in practice means not using it on the skin.

What is the difference between Indian and European sweet flag?

They differ in ploidy and hence in beta-asarone content. The European triploid form has 9–19 % in the rhizome oil, the Asian tetraploid 85–95 %, the American diploid contains none.

What can replace calamus in a meditation blend?

Frankincense, myrrh and Himalayan cedar. They give a similarly deep, earthy scent without the risk of asarone.

May calamus be used in food and cosmetics?

Beta-asarone must not be added to food in the EU and tetraploid sweet flag must not be used to make flavourings. For cosmetics the IFRA limit of 0.01 % asarone in the finished product applies.

Recommended Products

• BIO Calamus, essential oil 10 ml – only for experienced users and only into the air, never on the skin.
• BIO Frankincense, essential oil 10 ml – a safer base for meditation blends.
• BIO Myrrh, essential oil 10 ml – a deep resinous note instead of calamus.
• BIO Himalayan cedar, essential oil 10 ml – warm wood for an earthy scent.
• Ceramic oil burner 9 × 7.5 cm – for a short scenting with a small dose.

Sources

• EMA/HMPC: Public statement on the use of herbal medicinal products containing asarone, 2005 – PDF
• IFRA Standard: cis- and trans-Asarone (Amendment 40, 2006) – PDF
• Regulation (EC) No 1334/2008 on flavourings, Annexes III and IV – EUR-Lex
• α-Asarone, β-asarone, and γ-asarone: Current status of toxicological evaluation, J Appl Toxicol 2021 – PubMed

Updated: 27 September 2026