Drug & supplement interaction

Cowslip + Leucovorin Calcium

Leucovorin Calcium brand name: Wellcovorin.

No Known Interaction
The bottom line No known interaction

We found no known interaction between Cowslip and Leucovorin Calcium 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.

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Interaction report

Cowslip and Leucovorin Calcium

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 Leucovorin Calcium and Cowslip 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.

Worth understanding: our licensed dataset holds no drug-interaction record for Cowslip at all — not against Leucovorin Calcium, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

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.

Cowslip safety at a glance

Cowslip overall Use caution Generally used in traditional teas, but human safety data are limited and some people may have allergic reactions.
Pregnancy Avoid Not enough safety information, so it is best avoided during pregnancy.
Breastfeeding Avoid Safety while breastfeeding is unknown, so avoid use.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Leucovorin Calcium and Cowslip? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Leucovorin Calcium’s Own FDA Label Lists

This is not an interaction — none of it involves Cowslip. These are the most notable effects listed in the ADVERSE REACTIONS section of Leucovorin Calcium’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 5 of them are worth acting on rather than waiting out — marked below.

  • A low white blood cell count Worth acting on mentioned in 5.8% of FDA reports for Leucovorin Calcium
  • A low platelet count Worth acting on
  • Kidney problems Worth acting on
  • Hives Worth acting on
  • A higher chance of infection Worth acting on
  • Mouth irritation or sores
  • Hair loss
  • Reduced appetite
  • Constipation
  • Diarrhea mentioned in 9.5% of FDA reports for Leucovorin Calcium

Showing the 10 most notable of 14 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Leucovorin Calcium. Read the label on DailyMed › Where a percentage is shown, it is the share of 19,003 voluntary FDA FAERS reports for Leucovorin Calcium that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Cowslip’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Cowslip side to compare — that is a limit of the record, not a statement that Cowslip has no side effects.

Everything else you take

See Every Supplement That Interacts With Leucovorin Calcium

This page covers Cowslip only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Leucovorin Calcium page lists 17 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 · 9 minor.

Open the Leucovorin Calcium interaction page

One more smart check

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

We hold 21 real supplement products containing Cowslip, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cowslip. Even though Cowslip itself has no known interaction with Leucovorin Calcium, 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 Cowslip and Leucovorin Calcium 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 Cowslip
Top half

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

29 days ago today
Medication Leucovorin Calcium
Top 25%

#537 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 Cowslip reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Cowslip and Leucovorin Calcium records this page draws on were last updated June 22, 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 Cowslip

What is Cowslip?

  • Cough and chest congestion
  • Bronchitis and sinus problems
  • Trouble sleeping
  • Anxiety and restlessness
  • Headache

Cowslip is a traditional European herb whose flowers and roots have long been used as a tea or syrup, mainly for coughs and congestion. Solid human studies are very limited, so its benefits are not well proven. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Primula veris · Primulaceae · Flowers and roots · Tea, tincture, syrup, capsules, dried herb

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

Cowslip: dosing

There is no well-established standardized dose for cowslip. Traditional use has involved teas made from the flowers or preparations of the root, but reliable dosing information from research is lacking.If you choose to use a cowslip product, follow the directions on the product label and do not exceed the suggested amount.

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

Read the full Cowslip monograph & all interactions
Medication

About Leucovorin

What Is Leucovorin Used For?

Brand name: Wellcovorin

Leucovorin is used to reduce the harmful effects of methotrexate when the body is slow to clear it, and to counteract accidental overdoses of drugs that block folic acid (called folic acid antagonists or DHFR inhibitors). It is also used to treat cerebral folate transport deficiency (FOLR1-CFTD), a rare genetic condition that prevents the brain from receiving enough folate.

The injectable forms — including leucovorin calcium injection and Vykoura — are additionally approved for rescue after high-dose methotrexate therapy, for treatment of megaloblastic anemia (a type of anemia caused by low folic acid) when oral treatment isn't possible, and for use alongside fluorouracil in treating metastatic colorectal cancer. Leucovorin calcium injection is specifically indicated for rescue after high-dose methotrexate in osteosarcoma.

Most-Reported Side Effects for Leucovorin Calcium

From FAERS, the FDA’s public side-effect reporting system (19,003 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Diarrhea 1,799 reports
Nausea 1,388 reports
Vomiting 1,135 reports
Neutropenia 1,094 reports
Fever 1,011 reports
See full Leucovorin drug information
Keep checking

Other Drugs & Cowslip

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

0Major
0Moderate
0Minor
2,829No known interaction
No interaction 2,829 drugs checked — show the list
Evidence & sources

Cowslip References

The 3 references that drive our Cowslip 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. Neubauer N, Marz RW. Placebo-controlled, randomized, double-blind, clincal trial with Sinupret sugar coated tablets on the basis of a therapy with antibiotics and decongestant nasal drops in acute sinusitis. Phytomedicine 1994;1:177-81.
  2. Marz RW, Ismail C, Popp MA. Action profile and efficacy of a herbal combination preparation for the treatment of sinusitis. Wien Med Wochenschr 1999;149:202-8.
  3. Peric A, Kovacevic SV, Gacesa D, Peric AV. Efficacy and safety of combined treatment of acute rhinosinusitis by herbal medicinal product Sinupret and mometasone furoate nasal spray. ENT Updates 2017;7(2):68-74. DOI

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 Cowslip and Leucovorin Calcium Together: Common Questions

Is it safe to take Cowslip with Leucovorin Calcium?
We do not list a known interaction between Cowslip and Leucovorin Calcium. 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.
Does Leucovorin Calcium interact with any supplements?
Yes. Leucovorin Calcium has documented interactions with 17 supplements in our database — Cowslip is not one of them. The Leucovorin Calcium interaction page linked on this page lists every one, ranked by severity.

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

Still Have a Question About Leucovorin Calcium and Cowslip?

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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.