Drug & supplement interaction

Horsetail + Acetaminophen, Caffeine, Pyrilamine

Acetaminophen, Caffeine, Pyrilamine brand name: Midol Max Strength Menstrual.

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

Horsetail has a moderate interaction with Acetaminophen, Caffeine, Pyrilamine. Theoretically, taking horsetail with diuretic drugs might increase potassium loss and the risk of hypokalemia.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Horsetail and Acetaminophen, Caffeine, Pyrilamine

Here is the interaction we found between these two, with the evidence behind it.

Moderate

DIURETIC DRUGS

Why this applies to Acetaminophen, Caffeine, Pyrilamine

Acetaminophen, Caffeine, Pyrilamine falls under DIURETIC DRUGS — the group Horsetail interacts with.

Theoretically, taking horsetail with diuretic drugs might increase potassium loss and the risk of hypokalemia.
Laboratory research shows that various species of horsetail have diuretic properties. Due to its diuretic effects, there has been concern that taking horsetail along with potassium-depleting diuretics might increase the risk for hypokalemia. However, pharmacokinetic research in humans shows that taking horsetail 900 mg daily for 4 days does not affect urinary excretion of electrolytes, including potassium and sodium, despite having a diuretic effect similar to taking hydrochlorothiazide 25 mg daily. It is unclear if taking horsetail for a longer duration would affect electrolyte levels. Until more is known, use with caution.
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 thing to know about Midol Max Strength (acetaminophen, caffeine, and pyrilamine): the reason it shows up on a list with diuretics is the caffeine. Caffeine has a mild water-pill (diuretic) effect of its own, and horsetail is also thought to act as a gentle diuretic. The worry is that stacking two diuretic effects could, in theory, nudge your potassium lower over time.

But I want to keep this in perspective. This is a theoretical concern, and the human research we have showed horsetail did not actually change potassium or sodium levels even though it increased urine flow. For occasional use of Midol, this is very unlikely to be a problem. If you take horsetail regularly or notice muscle cramps, weakness, or an irregular heartbeat, check in with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Perez Gutierrez RM, Laguna GY, Walkowski A. Diuretic activity of Mexican equisetum. J Ethnopharmacol 1985;14:269-72. PubMed
  2. Lemus I, Garcia R, Erazo S, et al. Diuretic activity of an Equisetum bogotense tea (Platero herb): evaluation in healthy volunteers. J Ethnopharmacol 1996;54:55-8. PubMed
  3. Carneiro DM, Freire RC, Honório TC, Zoghaib I, Cardoso FF, Tresvenzol LM, de Paula JR, Sousa AL, Jardim PC, da Cunha LC. Randomized, Double-Blind Clinical Trial to Assess the Acute Diuretic Effect of Equisetum arvense (Field Horsetail) in Healthy Voluntee

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

Horsetail Also Interacts With Other Medications

Horsetail has 187 moderate known drug interactions in our database — the Acetaminophen, Caffeine, Pyrilamine one above is one of them. If you take anything else, check it against the full list below.

Moderate 187 No known interaction 2,643 (incl. Acetaminophen, Caffeine, Pyrilamine)
Taking anything else?

Check Another of Your Medications Against Horsetail

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

From our Q&A

Questions About Horsetail or Acetaminophen, Caffeine, Pyrilamine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Horsetail or Acetaminophen, Caffeine, Pyrilamine, 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 Acetaminophen, Caffeine, Pyrilamine

This page covers Horsetail only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Caffeine, Pyrilamine page lists 322 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Ephedra (major) and Grapefruit (major).

By severity: 16 major · 260 moderate · 46 minor.

Open the Acetaminophen, Caffeine, Pyrilamine interaction page

One more smart check

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

We hold 2,089 real supplement products containing Horsetail, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Horsetail. Your product may carry other ingredients that interact with Acetaminophen, Caffeine, Pyrilamine too, on top of Horsetail — 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 Horsetail and Acetaminophen, Caffeine, Pyrilamine 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 Horsetail
Top 10%

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

29 days ago today
Medication Acetaminophen, Caffeine, Pyrilamine
Top half

#922 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 Horsetail

What is Horsetail?

Horsetail
  • Fluid retention (mild diuretic)
  • Urinary and bladder concerns
  • Hair, skin, and nail support
  • Wound healing
  • Bone health

Horsetail is a traditional herb most often used as a mild diuretic and for hair, nail, and bone support, but high-quality human evidence is limited. It can cause thiamine (vitamin B1) loss with long-term use, and some related species are toxic, so choose products carefully and talk to your pharmacist or doctor before using it.

Read the full Horsetail monograph & all interactions
Keep checking

Other Drugs & Horsetail

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

0Major
187Moderate
0Minor
2,642No known interaction
187 Moderate 2,642 No interaction
Moderate

187 interactions

Showing 60 of 187 moderate interactions — see all 187 on the Horsetail page.

No interaction 2,642 drugs checked — show the list

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

Showing the 60 most looked-up of 2,642 medications checked with no known interaction — see the full Horsetail list.

See the full Horsetail interactions page
See every supplement checked against Acetaminophen, Caffeine, Pyrilamine, 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
Horsetail monograph › Uses, safety, and every drug interaction in one place Acetaminophen, Caffeine, Pyrilamine supplement interactions › Every supplement checked against Acetaminophen, Caffeine, Pyrilamine, 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 Horsetail and Acetaminophen, Caffeine, Pyrilamine Together: Common Questions

Can you take Horsetail with Acetaminophen, Caffeine, Pyrilamine?
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.
How serious is the Horsetail and Acetaminophen, Caffeine, Pyrilamine 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

Still Have a Question About Acetaminophen, Caffeine, Pyrilamine and Horsetail?

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.