Drug & supplement interaction

Clubmoss + Hydroxyurea

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

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Clubmoss 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.

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Interaction report

Clubmoss 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 Clubmoss 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.

Clubmoss safety at a glance

Clubmoss overall Use caution It contains toxic alkaloids and has limited safety data, so it should be used carefully if at all.
Pregnancy Possibly Unsafe When used orally; avoid using. Read the full pregnancy detail
Breastfeeding Possibly 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 Clubmoss? 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. Clubmoss has documented interactions with 3 drug classes — the most serious being acetylcholinesterase (ache) inhibitors (moderate), anticholinergic 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

Clubmoss Does Interact With Other Medications

Clubmoss has 219 moderate 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 219 No known interaction 2,611 (incl. Hydroxyurea)
Taking anything else?

Check Another of Your Medications Against Clubmoss

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

What to actually watch for

No Interaction Found — But Data Suggests Clubmoss 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.

  • Dizziness / Nausea reported in 6.2% of FDA reports for Hydroxyurea Additional detail

    Clubmoss

    “Clubmoss (Lycopodium clavatum) might be mistaken for fir club moss (Lycopodium selago), which contains huperzine A, a constituent with strong inhibitory activity against acetylcholinesterase. In two case reports, fir club moss was mistaken for clubmoss and ingested as tea. This caused cholinergic toxicity with symptoms of sweating, nausea, dizziness, cramping, and slurred speech.”

    Clubmoss · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 13193. Felgenhauer N, Zilker T, Worek F, Eyer P. Intoxication with huperzine A, a potent anticholinesterase found in the fir club moss. J Toxicol Clin Toxicol 2000;38:803-8.. 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 Clubmoss but not commonly for Hydroxyurea: sweating and wheezing.

Effects for Hydroxyurea come from the ADVERSE REACTIONS section of its FDA label; effects for Clubmoss 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

Clubmoss in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly 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

From our Q&A

Questions About Clubmoss 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 Clubmoss 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 Clubmoss 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

How much people look this up

Where Clubmoss 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 Clubmoss
Steady interest

#1,286 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Hydroxyurea
Top 5%

#39 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 Clubmoss reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Clubmoss 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 .
Supplement

About Clubmoss

What is Clubmoss?

Clubmoss
  • Bladder and kidney complaints
  • Digestive upset
  • Skin irritation and chafing
  • Respiratory problems
  • Used in homeopathy

Clubmoss (Lycopodium clavatum) is a primitive plant with a long history in folk medicine and homeopathy, but there is very little reliable human research to show it works for any health condition. It contains potentially toxic alkaloids, so it should be used with great caution, and people who are pregnant or breastfeeding should avoid it. Talk with a pharmacist or doctor before trying it.

Lycopodium clavatum · Lycopodiaceae · Whole plant and spores · Powdered spores, dried herb, tinctures, teas, homeopathic preparations, capsules

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

Clubmoss: dosing

There is no established, well-studied dose for clubmoss. Because the amount of active and potentially toxic compounds can vary between products and plant sources, a safe dose has not been clearly defined.If you choose to use a clubmoss product, follow the directions on the label and do not exceed them. Homeopathic "Lycopodium" products are extremely diluted and are different from raw herb preparations.

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

Read the full Clubmoss 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 & Clubmoss

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

0Major
219Moderate
0Minor
2,610No known interaction
219 Moderate 2,610 No interaction
Moderate

219 interactions

Showing 60 of 219 moderate interactions — see all 219 on the Clubmoss page.

No interaction 2,610 drugs checked — show the list

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

Showing the 60 most looked-up of 2,610 medications checked with no known interaction — see the full Clubmoss list.

See the full Clubmoss interactions page
See every supplement checked against Hydroxyurea, ranked by severity
Evidence & sources

Clubmoss References

The 3 references that drive our Clubmoss 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.

  1. Felgenhauer N, Zilker T, Worek F, Eyer P. Intoxication with huperzine A, a potent anticholinesterase found in the fir club moss. J Toxicol Clin Toxicol 2000;38:803-8.. PubMed
  2. Orhan, I., Terzioglu, S., and Sener, B. Alpha-onocerin: an acetylcholinesterase inhibitor from Lycopodium clavatum. Planta Med. 2003;69(3):265-267.
  3. Cullinan, P., Cannon, J., Sheril, D., and Newman, Taylor A. Asthma following occupational exposure to Lycopodium clavatum in condom manufacturers. Thorax 1993;48(7):774-775. PubMed

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 Clubmoss and Hydroxyurea Together: Common Questions

Is it safe to take Clubmoss with Hydroxyurea?
We do not list a known interaction between Clubmoss 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 Clubmoss 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.
How was the Clubmoss and Hydroxyurea combination checked?
Interactions in our licensed database are recorded against drug classes. Hydroxyurea is filed under 2 classifications, and Clubmoss has documented interactions with 3 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 Clubmoss interact with any other medications?
Yes. Clubmoss has 219 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 — Clubmoss 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

Clubmoss 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 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Hydroxyurea and Clubmoss?

Our pharmacists answer your medication & supplement questions — free.

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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.