Drug & supplement interaction

Calamus + Hydroxyurea

Hydroxyurea brand names: Droxia, Hydrea, Siklos, Xromi.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Calamus and Hydroxyurea in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

Know someone taking this? Share

Facebook Post Reddit Email

On this page

Interaction report

Calamus and Hydroxyurea

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Hydroxyurea and Calamus in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Calamus safety at a glance

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

Pregnancy Likely Unsafe When used orally; avoid using. Read the full pregnancy detail

Breastfeeding Likely Unsafe When used orally; avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Hydroxyurea and Calamus? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Hydroxyurea

Interactions in our licensed database are recorded against drug classes, not just single drug names. Hydroxyurea is filed under 2 classifications — antineoplastics, oral drugs. Calamus has documented interactions with 10 drug classes — the most serious being anticholinergic drugs (moderate), antihypertensive drugs (moderate) and cholinergic drugs (moderate) — and none of Hydroxyurea’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Calamus Does Interact With Other Medications

Calamus has 1,098 moderate, 19 minor known drug interactions in our database — Hydroxyurea isn’t one of them. If you take anything else, check it against the full list below.

Moderate 1,098 Minor 19 No known interaction 1,713 (incl. Hydroxyurea)

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.

What to actually watch for

No Interaction Found — But Data Suggests Calamus and Hydroxyurea May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

Nausea / Vomiting reported in 6.2% of FDA reports for Hydroxyurea Additional detail
Calamus
“A case of gastrointestinal toxicity has been reported in a 19-year-old male who appeared to use calamus root for its euphoric effects. The man ingested a large amount of the root with water and later presented at the emergency department with continuous vomiting, paleness, and sweating. He was treated intravenously with saline and promethazine.”

Calamus · Natural Medicines adverse-effect record, reported in nausea and vomiting.
3 sources cited

38458. Vargas, C. P., Wolf, L. R., Gamm, S. R., and Koontz, K. Getting to the root (Acorus calamus) of the problem. J Toxicol Clin Toxicol 1998;36(3):259-260.

93980. Björnstad K, Helander A, Hultén P, Beck O. Bioanalytical investigation of asarone in connection with Acorus calamus oil intoxications. J Anal Toxicol 2009;33(9):604-9. PubMed

33310. Shoba, F. G. and Thomas, M. Study of antidiarrhoeal activity of four medicinal plants in castor-oil induced diarrhoea. J Ethnopharmacol 2001;76(1):73-76. PubMed
Hydroxyurea

Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for Calamus but not commonly for Hydroxyurea: a fast or pounding heartbeat and sweating.

Effects for Hydroxyurea come from the ADVERSE REACTIONS section of its FDA label; effects for Calamus come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 21,027 voluntary FDA FAERS reports for Hydroxyurea that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Calamus in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Unsafe

When used orally; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Overlapping uses

What Hydroxyurea Is Prescribed For, and What Calamus Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Hydroxyurea is a prescription medicine with approved uses on its FDA label. Calamus is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Hydroxyurea is prescribed for: Hydroxyurea is used for several serious conditions. Droxia, Siklos, and Xromi are each indicated to reduce the frequency of painful crises and reduce the need for blood transfusions in patients with sickle cell anemia who have recurrent moderate to severe painful crises. Siklos is approved for adults and children 2 years and older; Xromi is approved for children 6 months and older; Droxia is approved for adults. Hydrea capsules and Hydroxyurea capsules are indicated for resistant chronic myeloid leukemia and for locally advanced squamous cell carcinomas of the head and neck (excluding the lip) when used together with chemoradiation.

Calamus has been studied for:

Cancer studied, not established Calamus has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

Calamus for cancer

Although there has been interest in using oral calamus for cancer, there is insufficient reliable information about the clinical effects of calamus for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Hydroxyurea on your own; if you are taking Calamus for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Calamus or Hydroxyurea

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Calamus or Hydroxyurea, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Hydroxyurea

This page covers Calamus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hydroxyurea page lists 18 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 10 minor.

From our pharmacist’s overview on the Hydroxyurea page

“People take hydroxyurea (Droxia, Hydrea, Siklos, Xromi) for serious reasons, most often sickle cell disease or certain blood cancers, and it only works if a steady dose reaches the bloodstream. That is exactly what nearly all 18 supplements listed here can undermine, so this page earns real vigilance rather than a skim.”

Reviewed by 2 · Jul 18, 2026

Open the Hydroxyurea 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. Even though Calamus itself has no known interaction with Hydroxyurea, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Calamus and Hydroxyurea 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

Steady interest

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

29 days ago today

Medication Hydroxyurea

Top 5%

#40 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.

Where does our data come from?

Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Calamus reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Calamus and Hydroxyurea records this page draws on were last updated July 10, 2026.
What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.

Data structure & sourcing designed and verified by Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Calamus

What is 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.

Acorus calamus · Acoraceae · Rhizome (root) and essential oil · Dried root, powder, tea, tincture, essential oil

An interaction check asks whether these two react with each other — it does not ask whether Calamus is a good idea for someone in your situation. Here is what our Calamus record says about it on its own.

Calamus: dosing

There is no established safe or effective dose for calamus. Because of the cancer and toxicity concerns, health authorities do not recommend a standard amount.If you come across a product that contains calamus, do not assume any amount is safe. For most people, the safest choice is to avoid calamus altogether and consider better-studied alternatives.

From our Calamus monograph — the full record covers uses, side effects and every documented interaction.

Read the full Calamus monograph & all interactions

Medication

About Hydroxyurea

What Is Hydroxyurea Used For?

Brand names: Droxia, Hydrea, Siklos, Xromi

Hydroxyurea is used for several serious conditions. Droxia, Siklos, and Xromi are each indicated to reduce the frequency of painful crises and reduce the need for blood transfusions in patients with sickle cell anemia who have recurrent moderate to severe painful crises. Siklos is approved for adults and children 2 years and older; Xromi is approved for children 6 months and older; Droxia is approved for adults.

Hydrea capsules and Hydroxyurea capsules are indicated for resistant chronic myeloid leukemia and for locally advanced squamous cell carcinomas of the head and neck (excluding the lip) when used together with chemoradiation.

Most-Reported Side Effects for Hydroxyurea

From FAERS, the FDA’s public side-effect reporting system (21,027 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 1,548 reports

Sickle cell anaemia with crisis 1,486 reports

Diarrhea 1,408 reports

Nausea 1,306 reports

Headache 1,068 reports

See full Hydroxyurea drug information

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

1,098Moderate

19Minor

1,712No known interaction

1,098 Moderate 19 Minor 1,712 No interaction

Moderate

1,098 interactions

Showing 60 of 1,098 moderate interactions — see all 1,098 on the Calamus page.

Minor

19 interactions

No interaction 1,712 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 1,712 medications checked with no known interaction — see the full Calamus list.

See the full Calamus interactions page

See every supplement checked against Hydroxyurea, ranked by severity

Evidence & sources

Calamus References

The 13 references that drive our Calamus monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
Brinker F. Herb Contraindications and Drug Interactions. Sandy, OR: Eclectic Medical Publ, 1997.
Shoba, F. G. and Thomas, M. Study of antidiarrhoeal activity of four medicinal plants in castor-oil induced diarrhoea. J Ethnopharmacol 2001;76(1):73-76. PubMed
Koo, B. S., Park, K. S., Ha, J. H., Park, J. H., Lim, J. C., and Lee, D. U. Inhibitory effects of the fragrance inhalation of essential oil from Acorus gramineus on central nervous system. Biol Pharm.Bull. 2003;26(7):978-982. PubMed
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
Panchal, G. M., Venkatakrishna-Bhatt, H., Doctor, R. B., and Vajpayee, S. Pharmacology of Acorus calamus L. Indian J Exp.Biol 1989;27(6):561-567.
Vargas, C. P., Wolf, L. R., Gamm, S. R., and Koontz, K. Getting to the root (Acorus calamus) of the problem. J Toxicol Clin Toxicol 1998;36(3):259-260.
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.
Sharma V, Singh I, Chaudhary P. Acorus calamus (The Healing Plant): a review on its medicinal potential, micropropagation and conservation. Nat Prod Res. 2014;28(18):1454-66.
Björnstad K, Helander A, Hultén P, Beck O. Bioanalytical investigation of asarone in connection with Acorus calamus oil intoxications. J Anal Toxicol 2009;33(9):604-9. PubMed
Federal Register. Volume 33, Page 6967. U.S. Government Publishing Office. http://api.fdsys.gov/link?collection=fr&volume=33&page=6967. Accessed May 23, 2018.
Electronic Code of Federal Regulations. Title 21. Part 189 - Substances Prohibited From Use in Human Food. Available at: https://www.ecfr.gov/cgi-bin/text-idx?SID=259fa8a1284cad42676075c8425c7333&mc=true&node=pt21.3.189&rgn=div5.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Calamus and Hydroxyurea Together: Common Questions

Is it safe to take Calamus with Hydroxyurea?

We do not list a known interaction between Calamus and Hydroxyurea. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.

Do Calamus and Hydroxyurea have any of the same side effects?

Yes — our sources link each of them separately to 2 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.

Are Calamus and Hydroxyurea used for the same thing?

They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Calamus in each. That is a conversation for your prescriber, especially if Hydroxyurea is being adjusted to a target.

How was the Calamus and Hydroxyurea combination checked?

Interactions in our licensed database are recorded against drug classes. Hydroxyurea is filed under 2 classifications, and Calamus has documented interactions with 10 drug classes — none of Hydroxyurea's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.

Does Calamus interact with any other medications?

Yes. Calamus has 1,117 documented drug interactions in our database — Hydroxyurea is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.

Does Hydroxyurea interact with any supplements?

Yes. Hydroxyurea has documented interactions with 18 supplements in our database — Calamus is not one of them. The Hydroxyurea interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Calamus monograph Uses, safety profile, and every drug interaction in one place Hydroxyurea drug information The full plain-English guide to this medication Hydroxyurea supplement interactions Every supplement checked against Hydroxyurea, 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 References The 13 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Hydroxyurea and Calamus?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.