Herb & supplement monograph

Clubmoss Drug Interactions, Uses, Safety & More

Medically reviewed by ·Updated July 2026
What is this page for?

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

But these pages have grown well beyond that into a full monograph — what Clubmoss 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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Clubmoss 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 Clubmoss drug interaction appears low for most people, since every listed concern is theoretical. None of the interactions are rated major, and all of them rest on lab research rather than studies in people.

Interactions deserving the most attention

The interactions that deserve the most thought all trace back to one lab finding: clubmoss may block the enzyme the body uses to break down acetylcholine, a key nerve-signaling chemical. That means it could theoretically add to the effects of acetylcholinesterase inhibitors such as donepezil, which are used for memory problems, raising the chance of side effects like nausea, slow heart rate, or excess salivation. It could also work against anticholinergic drugs such as atropine or benztropine, possibly making either the drug or the supplement less effective. None of these effects has been confirmed in humans.

What the rest of the list means

The long list of interacting medications looks more concerning than it is. Every entry stems from that single lab observation about one enzyme, applied across many drugs that touch the same pathway. Whether clubmoss actually causes meaningful changes in people taking these medicines has not been shown.

Check your medications against Clubmoss

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

Interaction report

Drugs that interact with Clubmoss

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

2,830 drugs
AcepromazineAtravet› Acetaminophen, Caffeine, Chlorpheniramine, Hydrocodone, PhenylephrineHycomine Compound› Acetaminophen, Caffeine, PyrilamineMidol Max Strength Menstrual› Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HbrVicks Formula 44M Cough, Cold & Flu Relief› Acetaminophen, Chlorpheniramine, Codeine, PhenylephrineColrex› Acetaminophen, Chlorpheniramine, DextromethorphanCoricidin II Extra Strength Cold and Flu› Acetaminophen, Chlorpheniramine, Dextromethorphan HydrobromideCoricidin HBP Maximum Strength Flu› Acetaminophen, Chlorpheniramine, Dextromethorphan, PhenylpropanolamineMulti Symptom Cold Relief› Acetaminophen, Chlorpheniramine, Dextromethorphan, PseudoephedrineChildren's Tylenol Cold Plus Cough, Tylenol Cold Ex Strength› Acetaminophen, Chlorpheniramine, Guaifenesin, Phenylephrine, SalicylamideRhinogesic GG› Acetaminophen, Chlorpheniramine, PhenylephrineAlka-Seltzer PLUS, Histex SR, Protid› Acetaminophen, Chlorpheniramine, Phenylephrine, SalicylamideRhinogesic, Rhinogesic JR› Acetaminophen, Chlorpheniramine, PhenylpropanolamineAlumadrine, Conex, Sinadrin Max Strength, Sinulin› Acetaminophen, Chlorpheniramine, Phenylpropanolamine, OpiumHista-Derfule› Acetaminophen, Chlorpheniramine, Phenylpropanolamine, PhenyltoloxamineNorel Plus› Acetaminophen, Chlorpheniramine, PseudoephedrineAlka-Seltzer PLUS Liquid Gels, Children's Tylenol Cold, Codimal, Comtrex, Extra Strength Tylenol Allergy Sinus, Lorsin +3 more› Acetaminophen, Codeine, DoxylamineMersyndol› Acetaminophen, Dextromethorphan, Doxylamine, PseudoephedrineVicks NyQuil› Acetaminophen, Dextromethorphan, Phenylpropanolamine, PyrilamineTheracaps› Acetaminophen, DiphenhydramineTylenol PM, Tylenol PM Ex Strength› Acetaminophen, Diphenhydramine, PseudoephedrineChildren's Tylenol Allergy, Cold Control, Contac Night Allergy Relief› Acetaminophen, Doxylamine, PseudoephedrineEx Strength Tylenol Sinus Nighttime› Acetaminophen, Pamabrom, PyrilamineMidol Max Strength PMS, Pamprin, Pamprin ES› Acetaminophen, Phenylephrine, ChlorpheniramineSuper Cold Tabs› AcetylcholineMiochol-E› Aclidinium BromideTudorza Pressair› Aclidinium Bromide, Formoterol Fumarate DihydrateDuaklir Pressair› Aerosphere Budesonide, Formoterol Fumarate, GlycopyrrolateBreztri› AmantadineGocovri, Osmolex ER, Symmetrel› Ambenonium ChlorideMytelase›
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 Clubmoss 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 Clubmoss affects

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

All 3 drug categories Clubmoss interacts with
Acetylcholinesterase (ache) InhibitorsAnticholinergic DrugsCholinergic Drugs
Acetylcholinesterase (Ache) Inhibitors

Evidence from in vitro research suggests that clubmoss extract can inhibit acetylcholinesterase activity. Theoretically, concurrent use of clubmoss with other acetylcholinesterase (AChE) inhibitors might have additive effects and increase the risk of cholinergic side effects. AChE inhibitors and cholinergic drugs include bethanechol (Urecholine), donepezil (Aricept), echothiophate (Phospholine Iodide), edrophonium (Enlon, Reversol, Tensilon), neostigmine (Prostigmin), physostigmine (Antilirium), pyridostigmine (Mestinon, Regonol), succinylcholine (Anectine, Quelicin), and tacrine (Cognex).

Likelihood Possible Evidence D
Anticholinergic Drugs

Evidence from in vitro research suggests that clubmoss extract can inhibit acetylcholinesterase activity. Theoretically, concurrent use of anticholinergic drugs and clubmoss might decrease the effectiveness of club moss or the anticholinergic agent. Some anticholinergic drugs include atropine, benztropine (Cogentin), biperiden (Akineton), procyclidine (Kemadrin), and trihexyphenidyl (Artane).

Likelihood Possible Evidence D
Cholinergic Drugs

Evidence from in vitro research suggests that clubmoss extract can inhibit acetylcholinesterase activity. Theoretically, concurrent use of clubmoss with other cholinergic drugs might have additive effects and increase the risk of cholinergic side effects. AChE inhibitors and cholinergic drugs include bethanechol (Urecholine), donepezil (Aricept), echothiophate (Phospholine Iodide), edrophonium (Enlon, Reversol, Tensilon), neostigmine (Prostigmin), physostigmine (Antilirium), pyridostigmine (Mestinon, Regonol), succinylcholine (Anectine, Quelicin), and tacrine (Cognex).

Likelihood Possible Evidence D
Monograph

Clubmoss: Uses, Safety & Side Effects

Medically reviewed by · Reviewed July 2026 ·
The bottom line

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.

Clubmoss
Scientific name
Lycopodium clavatum
Family
Lycopodiaceae
Part used
Whole plant and spores
Common forms
Powdered spores, dried herb, tinctures, teas, homeopathic preparations, capsules
People commonly use it for
  • Bladder and kidney complaints
  • Digestive upset
  • Skin irritation and chafing
  • Respiratory problems
  • Used in homeopathy

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

Safety at a glance
OverallUse caution

It contains toxic alkaloids and has limited safety data, so it should be used carefully if at all.

PregnancyPossibly Unsafe

When used orally; avoid using.

Read the full pregnancy detail
BreastfeedingPossibly 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

Clubmoss usually refers to Lycopodium clavatum, a low-growing, evergreen plant in the Lycopodiaceae family. It is not a true moss or a fern, but it does belong to an ancient group of spore-producing plants. It has small, scale-like leaves and creeping stems, and it grows in many parts of the world, including North America, Europe, and Asia, often in forests, heaths, and mountain areas.

People have used clubmoss in traditional and folk medicine for a very long time. The fine yellow spore powder (sometimes called lycopodium powder) was historically used as a dusting powder for skin and on pills, and even in early photography and fireworks because it is highly flammable. Today, clubmoss is most often seen in homeopathic products, herbal teas, tinctures, and powders.

Uses & effectiveness

Clubmoss has traditionally been used for bladder and kidney problems, digestive complaints, skin irritation and chafing, and respiratory issues. In homeopathy, very diluted "Lycopodium" preparations are promoted for many different conditions. None of these traditional or homeopathic uses are supported by strong human evidence.

Some laboratory and animal studies have looked at compounds related to clubmosses for possible anti-inflammatory and antioxidant effects, and certain alkaloids found in some Huperzia species (close relatives) have been studied for memory and the brain. However, Lycopodium clavatum itself has not been shown in good-quality human trials to treat or cure any disease. Overall, the evidence for clubmoss is weak and mostly preliminary.

How it works

Clubmoss contains a mix of plant compounds, including alkaloids such as lycopodine and dihydrolycopodine, along with flavonoids and other substances. Some of these compounds have shown antioxidant or anti-inflammatory activity in test-tube and animal experiments.

It is important to know that these findings come from the lab, not from solid human studies. The amounts of active compounds in a clubmoss product can vary a lot, and we do not have a clear picture of how the plant behaves in the human body. So any proposed "mechanism" should be seen as a theory, not a proven effect.

Safety & precautions

Clubmoss should be used cautiously. The plant contains alkaloids, including lycopodine, and even small traces of nicotine-like compounds, that can be toxic in larger amounts. Taking the herb internally may not be safe, and the safety of long-term use is unknown.

People with kidney problems, heart conditions, or other chronic illnesses should be especially careful and check with a healthcare provider first. The flammable spore powder should be kept away from heat and flames. Children and older adults should not use clubmoss without medical guidance.

Pregnancy and breastfeeding: Because clubmoss contains potentially toxic compounds and there is not enough safety information, it should be avoided during pregnancy and while breastfeeding.

Side effects

Because clubmoss is not well studied in people, the full range of side effects is not known. Possible problems include stomach upset, nausea, and skin irritation, especially with the powder. Allergic reactions are possible in sensitive people.

Taking too much of the plant or its alkaloids could cause more serious toxic effects. If you notice symptoms such as severe stomach pain, vomiting, dizziness, a fast or irregular heartbeat, trouble breathing, or a rash, stop using it and seek medical care right away.

Clubmoss: Reported Adverse Effects

Documented safety reports on Clubmoss from the evidence-graded Natural Medicines (TRC Healthcare) database, shown word-for-word from the licensed record.

Orally, no adverse effects have been reported; however, a thorough evaluation of safety outcomes has not been conducted. Additionally, clubmoss contains toxic alkaloids, which could cause serious adverse effects. When fir club moss (Lycopodium selago) is mistaken for clubmoss, cholinergic toxicity has been reported. This toxicity is due to huperzine A, which is not present in clubmoss.

Airborne exposure to clubmoss spores might cause symptoms of asthma.

  1. 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.
  2. 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..
Reports by condition
Asthma Pulmonary/Respiratory

Occupational exposure to clubmoss spores, including cases associated with facilities that use the spores to coat condoms, has been reported to cause asthma.

  1. 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.
Nausea and vomiting Other

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.

  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..
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.

Adverse-effects data: Natural Medicines, Therapeutic Research Center

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. Always talk with a pharmacist or doctor before using clubmoss, and let them know about any other medicines or supplements you take.

Pregnancy & Breastfeeding

Clubmoss & Pregnancy

Possibly Unsafe

When used orally; avoid using.

Clubmoss & Breastfeeding

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

Pregnancy & lactation ratings: Natural Medicines, Therapeutic Research Center

References & further reading

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
Keep reading

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.

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

Pharmacist Counseling Corner

Clubmoss: Common Questions

Does Clubmoss interact with prescription medications?
Yes. We list 219 medications with a known interaction with Clubmoss. Use the checker above to see how Clubmoss interacts with a specific drug.
How are Clubmoss interactions rated?
Each interaction is graded major, moderate, or minor based on how clinically significant it is and the strength of the evidence behind it. Major interactions are the most serious and are best avoided, or used only under close professional supervision.
Is it safe to take Clubmoss with my medications?
It depends on the specific medication. Some combinations are fine, while others call for monitoring, timing changes, or should be avoided. Check your exact drug above and confirm with your pharmacist or doctor before starting, stopping, or changing anything.
Where does this Clubmoss interaction information come from?
Our interaction data is built on the Natural Medicines database — an evidence-graded reference for vitamins, herbs, and supplements — and is reviewed by licensed HelloPharmacist pharmacists, who may add clinical context.
What is Clubmoss used for?
It has traditionally been used for bladder and kidney complaints, digestive upset, skin irritation, and breathing problems, and it appears in many homeopathic products. However, there is no strong human evidence that it works for any of these uses.
Is Clubmoss safe to take?
Clubmoss contains potentially toxic alkaloids and has very limited safety data, so it should be used with caution, if at all. It is best to check with a pharmacist or doctor before using it.
Can I use Clubmoss while pregnant or breastfeeding?
No. Because it contains potentially toxic compounds and there is not enough safety information, Clubmoss should be avoided during pregnancy and breastfeeding.
Is homeopathic Lycopodium the same as the Clubmoss herb?
Not exactly. Homeopathic "Lycopodium" is made from Clubmoss but is extremely diluted, while herbal preparations may contain much higher amounts of the plant's compounds. They should not be assumed to be the same in strength or safety.

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

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