Drug & supplement interaction

Calamus + Olodaterol Hydrochloride, Tiotropium Bromide

Olodaterol Hydrochloride, Tiotropium Bromide brand name: Stiolto Respimat.

Moderate Interaction
Medically reviewed by · Updated October 2026
The bottom line Moderate

Olodaterol Hydrochloride, Tiotropium Bromide falls into 2 drug categories that Calamus can interact with; the most serious is rated moderate. Theoretically, taking calamus with drugs metabolized by CYP3A4 might increase drug levels and potentially increase the risk of adverse effects.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Calamus and Olodaterol Hydrochloride, Tiotropium Bromide

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Calamus interacts with whole categories of medication. Olodaterol Hydrochloride, Tiotropium Bromide falls into 2 of those categories, so it can interact with Calamus in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

1 of 2

Why this applies to Olodaterol Hydrochloride, Tiotropium Bromide

Olodaterol Hydrochloride, Tiotropium Bromide falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Calamus interacts with.

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.
Severity Moderate Likelihood Possible Evidence D

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the basic idea: Stiolto Respimat combines olodaterol and tiotropium, and olodaterol is partly broken down by a liver enzyme called CYP3A4. In lab (test-tube) studies, calamus appears to slow that enzyme down. In theory, that could let a little more olodaterol linger in your body, which might nudge up its usual side effects, things like a faster or pounding heartbeat, jitteriness, tremor, or a headache.

I want to be honest about how thin this evidence is. This is only test-tube data, not something proven in people, so the real-world risk is probably small. Still, calamus carries its own safety concerns (it's banned from foods in the U.S.), so I'd skip it and check with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pandit S, Mukherjee PK, Ponnusankar S, Venkatesh M, Srikanth N. Metabolism mediated interaction of a-asarone and Acorus calamus with CYP3A4 and CYP2D6. Fitoterapia 2011;82(3):369-74.
Moderate

ANTICHOLINERGIC DRUGS

2 of 2

Olodaterol Hydrochloride, Tiotropium Bromide also falls under 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).
Severity Moderate Likelihood Possible Evidence D

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.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Stiolto Respimat pairs two inhaled medicines for COPD. One of them, tiotropium, is an anticholinergic, meaning it works by blocking the chemical messenger acetylcholine in your airways to help keep them open and ease breathing. Calamus seems to do the opposite in lab studies: it blocks the enzyme that normally clears acetylcholine away, so more of that messenger sticks around. In theory, that extra acetylcholine could work against tiotropium and make your inhaler a little less effective, leaving you more short of breath or wheezy.

I want to be honest that this is based only on test-tube research, not real people, so we really don't know if it matters in everyday use. Given calamus also carries its own safety concerns, I'd skip it and chat with your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Oh, M. H., Houghton, P. J., Whang, W. K., and Cho, J. H. Screening of Korean herbal medicines used to improve cognitive function for anti-cholinesterase activity. Phytomedicine 2004;11(6):544-548. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction 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.
  • PossibleInteraction 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.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Calamus Also Interacts With Other Medications

Calamus has 1,099 moderate, 19 minor known drug interactions in our database — the Olodaterol Hydrochloride, Tiotropium Bromide one above is among them. If you take anything else, check it against the full list below.

Moderate 1,099 Minor 19 No known interaction 1,712 (incl. Olodaterol Hydrochloride, Tiotropium Bromide)
Taking anything else?

Check Another of Your Medications Against Calamus

Covers the 2,830 medications we’ve checked against Calamus. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Olodaterol Hydrochloride, Tiotropium Bromide

This page covers Calamus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Olodaterol Hydrochloride, Tiotropium Bromide page lists 171 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: American Hellebore (major), Arsenic (major), Cesium (major), Ephedra (major) and Grapefruit (major).

By severity: 9 major · 133 moderate · 29 minor.

Open the Olodaterol Hydrochloride, Tiotropium Bromide interaction page

One more smart check

Taking Calamus as Part of a Dietary Supplement Product? Check It for Interactions

We hold 71 real supplement products containing Calamus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Calamus. Your product may carry other ingredients that interact with Olodaterol Hydrochloride, Tiotropium Bromide too, on top of Calamus — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Calamus and Olodaterol Hydrochloride, Tiotropium Bromide Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Calamus
Top half

#524 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Olodaterol Hydrochloride, Tiotropium Bromide
Top 5%

#100 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Calamus

What is Calamus?

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

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.

Read the full Calamus monograph & all interactions
Keep checking

Other Drugs & Calamus

Browse every other medication we’ve checked against Calamus — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
1,099Moderate
19Minor
1,711No known interaction
1,099 Moderate 19 Minor 1,711 No interaction
Moderate

1,099 interactions

Showing 60 of 1,099 moderate interactions — see all 1,099 on the Calamus page.

Minor

19 interactions

No interaction 1,711 drugs checked — show the list

We also checked Calamus against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,711 medications checked with no known interaction — see the full Calamus list.

See the full Calamus interactions page
See every supplement checked against Olodaterol Hydrochloride, Tiotropium Bromide, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Calamus monograph › Uses, safety, and every drug interaction in one place Olodaterol Hydrochloride, Tiotropium Bromide supplement interactions › Every supplement checked against Olodaterol Hydrochloride, Tiotropium Bromide, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Calamus and Olodaterol Hydrochloride, Tiotropium Bromide Together: Common Questions

Can you take Calamus with Olodaterol Hydrochloride, Tiotropium Bromide?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Calamus and Olodaterol Hydrochloride, Tiotropium Bromide?
Olodaterol Hydrochloride, Tiotropium Bromide belongs to more than one drug category, and Calamus interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Calamus and Olodaterol Hydrochloride, Tiotropium Bromide interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.