Herb & supplement monograph

Calamus Drug Interactions, Uses, Effectiveness, Safety & More

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS ·Updated July 2026

What is this page for?

First and foremost: how Calamus interacts with medications. The heart of this page is the interaction list — every drug Calamus is known to interact with, and how serious each one is.

But these pages have grown well beyond that into a full monograph — what Calamus is, what people use it for and how strong the evidence is, its safety and side effects, and answers to the questions we’re asked most — written and reviewed by the clinical staff at HelloPharmacist. It’s educational information from our licensed clinical databases, not medical advice, and we don’t sell or endorse products. Our editorial policy

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On this page

Calamus Drug Interactions: The Bottom Line

From the HelloPharmacist Editorial Team · Updated July 2026

Based on the available evidence, the overall risk of a clinically significant Calamus drug interaction appears low for most people, since none of its known interactions are rated major or confirmed in human studies. Most of the interactions are rated moderate, but every one of them rests on lab or animal research rather than documented effects in people.

Interactions deserving the most attention

The combinations worth the most care involve MAOIs, where some reports suggest calamus may strengthen both their effects and their side effects. Because animal research suggests calamus can slow the heart and act as a sedative, we would also watch blood pressure medications and CNS depressants such as sedatives, where added drowsiness or low blood pressure could matter. Effects on stomach acid drugs like antacids and PPIs are considered minor.

What the rest of the list means

The long list of medications is mostly explained by lab findings that calamus may block enzymes the body uses to clear many common drugs, which could in theory raise drug levels. That is a prediction, not a proven effect, and none of these interactions has been confirmed to cause meaningful changes in people.

Check your medications against Calamus

Based on HelloPharmacist’s Calamus interaction data and reviewed under our editorial standards.

Interaction report

Drugs that interact with Calamus

1119 medications have a known interaction with Calamus, graded by severity. Select any drug for the full evidence-based detail.

Don’t want to scroll the list? Just ask.

Tell us the medications you take and we’ll check each one against Calamus using our pharmacist-reviewed interaction data.

AI summaries are generated from our Calamus interaction data for education only — always confirm with your pharmacist. How we use AI

2,830 drugs

Read The List Like a Pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
Probable. Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
Possible. Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists
Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
Each drug listed above links to the full report for that exact Calamus combination — clinical detail, likelihood, evidence level, and citations.
Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

The big picture

The kinds of drugs Calamus affects

Every type of medication (drug category) Calamus is known to interact with. Open any category for the detail — or search your exact drug in the checker above.

All 10 drug categories Calamus interacts with

Anticholinergic DrugsAntihypertensive DrugsCholinergic DrugsCns DepressantsCytochrome P450 2d6 (cyp2d6) SubstratesCytochrome P450 3a4 (cyp3a4) SubstratesMonoamine Oxidase Inhibitors (maois)AntacidsH2-blockersProton Pump Inhibitors (ppis)

Anticholinergic Drugs

Theoretically, concurrent use of anticholinergic drugs and calamus might decrease the effectiveness of the anticholinergic drug.
In vitro evidence shows that calamus can inhibit acetylcholinesterase (AChE).

Likelihood Possible Evidence D

Antihypertensive Drugs

Theoretically, taking calamus with other antihypertensive medications might increase the risk of hypotension.
Animal research shows that calamus decreases the rate and strength of the heartbeat, which might lower blood pressure. use with caution.

Likelihood Possible Evidence D

Cholinergic Drugs

Theoretically, concurrent use of cholinergic drugs and calamus might have an additive effect and increase the risk of cholinergic effects.
In vitro evidence shows that calamus can inhibit acetylcholinesterase (AChE).

Likelihood Possible Evidence D

Cns Depressants

Theoretically, concurrent use of CNS depressants and calamus might have an additive effect and increase the risk of sedative effects.
Animal research shows that calamus is a CNS depressant and increases gamma-aminobutyric acid levels.

Likelihood Possible Evidence D

Cytochrome P450 2D6 (Cyp2D6) Substrates

Theoretically, taking calamus with drugs metabolized by CYP2D6 might increase drug levels and potentially increase the risk of adverse effects.
In vitro research shows that calamus extract inhibits CYP2D6 enzyme.

Likelihood Possible Evidence D

Cytochrome P450 3A4 (Cyp3A4) Substrates

Theoretically, taking calamus with drugs metabolized by CYP3A4 might increase drug levels and potentially increase the risk of adverse effects.
In vitro research shows that calamus extract inhibits CYP3A4 enzyme.

Likelihood Possible Evidence D

Monoamine Oxidase Inhibitors (Maois)

Theoretically, calamus might potentiate the effects and adverse effects of MAOIs.
Some reports suggest that calamus increases the effects of MAOIs.

Likelihood Possible Evidence D

Antacids

Theoretically, taking calamus might reduce the effectiveness of antacids.
Some research suggests that calamus lowers gastric pH.

Likelihood Possible Evidence D

H2-Blockers

Theoretically, taking calamus might reduce the effectiveness of H2-blockers.
Some research suggests that calamus lowers gastric pH.

Likelihood Possible Evidence D

Proton Pump Inhibitors (Ppis)

Theoretically, taking calamus might reduce the effectiveness of PPIs.
Some research suggests that calamus lowers gastric pH.

Likelihood Possible Evidence D

Monograph

Calamus: Uses, Safety & Side Effects

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Reviewed July 2026 ·

The bottom line

Calamus is a swamp plant with a long history in Ayurvedic and traditional Chinese medicine, mostly for digestive and nervous-system complaints. However, it contains beta-asarone, a compound linked to cancer and other toxic effects in animal studies, which is why the U.S. FDA banned it from foods. Because of these safety concerns and a lack of solid human evidence, it is generally best avoided.

Scientific name: Acorus calamus
Family: Acoraceae
Part used: Rhizome (root) and essential oil
Common forms: Dried root, powder, tea, tincture, essential oil

People commonly use it for

Digestive upset and gas
Loss of appetite
Memory and focus (traditional)
Coughs and colds
Calming or sedative effect (traditional)

Popular and traditional uses — not proof it works. See “Uses & effectiveness” below for the evidence.

Safety at a glance

OverallBest avoided

Some forms contain beta-asarone, a possible carcinogen banned from food by the FDA.

PregnancyLikely Unsafe

When used orally; avoid using.

Read the full pregnancy detail

BreastfeedingLikely Unsafe

When used orally; avoid using.

Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center). Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Jump to a section

Overview

Calamus (Acorus calamus) is a tall, grass-like wetland plant that grows in marshes, swamps, and along the edges of ponds and streams. It is found in parts of Europe, Asia, and North America. The part most often used is the underground stem, called the rhizome, which has a strong, spicy smell.

For centuries, calamus has been used in traditional medicine systems such as Ayurveda and traditional Chinese medicine. People have used it for stomach and digestive problems, to boost appetite, to support memory, and as a calming remedy. It has also been used as a flavoring and in perfumes.

Despite this long history, modern safety reviews have raised serious red flags about certain chemicals in the plant. As a result, calamus is no longer allowed as a food additive in the United States.

How it works

Calamus contains several active compounds, including essential oils with substances called alpha-asarone and beta-asarone. The amount of these compounds varies a lot depending on the plant's variety and where it grows.

In laboratory and animal research, calamus extracts have shown possible effects on the digestive tract, the nervous system, and on inflammation. Some studies suggest it may relax smooth muscle or have mild calming effects.

It is important to remember that these findings come mostly from test-tube and animal studies, not from well-designed human trials. So we cannot be sure these effects happen, or are helpful, in people.

Effectiveness

Does Calamus work?

Here’s what the research actually shows for each use — graded by Natural Medicines and reviewed by Dr. Brian Staiger, PharmD.

Evidence overview · 21 uses evaluated

21 Insufficient evidence

How to read these evidence grades

Natural Medicines’ 7-point scale. We show each rating’s label word-for-word.

1EffectiveStrong, consistent evidence it works.

2Likely EffectiveGood evidence, though not yet conclusive.

3Possibly EffectiveSome evidence suggests a benefit.

4Possibly IneffectiveSome evidence it may not help.

5Likely IneffectiveFairly strong evidence it doesn’t help.

6IneffectiveStrong evidence it doesn’t work.

7Insufficient Reliable Evidence to RateToo little research to say either way.

For Calamus, current evidence isn’t strong enough to rate any specific use. The conditions it has been studied for are listed below.

Also studied for 21 conditions — evidence insufficient to rate

Insufficient Reliable Evidence To Rate Anorexia nervosa