Drug & supplement interaction

Willow Bark + Tofacitinib

Tofacitinib brand names: Xeljanz, Xeljanz XR.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Willow Bark and Tofacitinib 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

Willow Bark and Tofacitinib

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 Tofacitinib and Willow Bark 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.

Willow Bark safety at a glance

Willow Bark overall Use caution Generally tolerated short-term by healthy adults, but it acts like aspirin and is not safe for everyone.
Pregnancy Avoid Avoid during pregnancy because its aspirin-like action may pose risks, especially later in pregnancy.
Breastfeeding Possibly Unsafe When used orally. Willow bark contains salicylates which are excreted in breast milk and have been linked to adverse effects in breast-fed infants. 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 Tofacitinib and Willow Bark? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Tofacitinib

Interactions in our licensed database are recorded against drug classes, not just single drug names. Tofacitinib is filed under 4 classifications — including cytochrome p450 2c19 (cyp2c19) substrates, immunosuppressants, cytochrome p450 3a4 (cyp3a4) substrates. Willow Bark has documented interactions with 5 drug classes — the most serious being acetazolamide (moderate), anticoagulant/antiplatelet drugs (moderate) and aspirin (moderate) — and none of Tofacitinib’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

Willow Bark Does Interact With Other Medications

Willow Bark has 127 moderate known drug interactions in our database — Tofacitinib isn’t one of them. If you take anything else, check it against the full list below.

Moderate 127 No known interaction 2,703 (incl. Tofacitinib)
Taking anything else?

Check Another of Your Medications Against Willow Bark

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

What to actually watch for

No Interaction Found — But Data Suggests Willow Bark and Tofacitinib 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. One of them is worth acting on rather than waiting out — marked below.

  • An allergic reaction Worth acting on Additional detail

    Willow Bark

    “Orally, willow bark seems to be well tolerated.

    Most Common Adverse Effects:

    Orally: Diarrhea, dyspepsia, heartburn, and vomiting. May cause itching and rash in sensitive individuals.

    Serious Adverse Effects (Rare):

    Orally: Gastrointestinal bleeding and renal impairment. May cause serious allergic reactions, including anaphylaxis, in people who are allergic to aspirin.”

    Willow Bark · Natural Medicines adverse-effect record, reported in diarrhea.

    Tofacitinib

    Listed in the ADVERSE REACTIONS section of the FDA label for Tofacitinib. Read the label on DailyMed ›

  • Headache reported in 7.3% of FDA reports for Tofacitinib Additional detail

    Willow Bark

    “Orally, willow bark may cause headache and dizziness. In a clinical trial evaluating a combination product containing willow bark, black cohosh, sarsaparilla, poplar bark, and guaiac wood (Reumalex), severe headaches occurred.”

    Willow Bark · Natural Medicines adverse-effect record, reported in cluster headache.

    2 sources cited
    1. 12804. Chrubasik S, Kunzel O, Model A, et al. Treatment of low back pain with a herbal or synthetic anti-rheumatic: a randomized controlled study. Willow bark extract for low back pain. Rheumatology (Oxford) 2001;40:1388-93. PubMed
    2. 35946. Mills SY, Jacoby RK, Chacksfield M, Willoughby M. Effect of a proprietary herbal medicine on the relief of chronic arthritic pain: a double-blind study. Br J Rheumatol 1996;35:874-8. PubMed

    Tofacitinib

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

  • Diarrhea Additional detail

    Willow Bark

    “Orally, willow bark extract can cause gastrointestinal adverse effects, but these appear to be less frequent than those caused by NSAIDs. Examples include diarrhea, heartburn, vomiting, and dyspepsia. In a case report of a child, severe gastrointestinal bleeding occurred following use of a specific syrup (FreddoBaby), which contained ribwort plantain, licorice, willow bark, black elder, meadowsweet, and propolis.”

    Willow Bark · Natural Medicines adverse-effect record, reported in diarrhea.

    5 sources cited
    1. 12474. Schmid B, Ludtke R, Selbmann HK, et al. Efficacy and tolerability of a standardized willow bark extract in patients with osteoarthritis: randomized placebo-controlled, double blind clinical trial. Phytother Res 2001;15:344-50. PubMed
    2. 12475. Biegert C, Wagner I, Ludtke R, et al. Efficacy and safety of willow bark extract in the treatment of osteoarthritis and rheumatoid arthritis: results of 2 randomized double-blind controlled trials. J Rheumatol 2004;31:2121-30.
    3. 12804. Chrubasik S, Kunzel O, Model A, et al. Treatment of low back pain with a herbal or synthetic anti-rheumatic: a randomized controlled study. Willow bark extract for low back pain. Rheumatology (Oxford) 2001;40:1388-93. PubMed
    4. 86459. Chrubasik, S., Kunzel, O., Black, A., Conradt, C., and Kerschbaumer, F. Potential economic impact of using a proprietary willow bark extract in outpatient treatment of low back pain: an open non-randomized study. Phytomedicine 2001;8(4):241-251. PubMed
    5. 86477. <p>Moro PA, Flacco V, Cassetti F, Clementi V, Colombo ML, Chiesa GM, Menniti-Ippolito F, Raschetti R, Santuccio C. Hypovolemic shock due to severe gastrointestinal bleeding in a child taking an herbal syrup. Ann Ist Super Sanita. 2011;47(3):278-83.</p>

    Tofacitinib

    Listed in the ADVERSE REACTIONS section of the FDA label for Tofacitinib. Read the label on DailyMed ›

  • A skin rash Additional detail

    Willow Bark

    “Orally, willow bark may cause itching and rash in some people due to allergy.”

    Willow Bark · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    5 sources cited
    1. 6456. Chrubasik S, Eisenberg E, Balan E, et al. Treatment of low back pain exacerbations with willow bark extract: a randomized double-blind study. Am J Med 2000;109:9-14. PubMed
    2. 12474. Schmid B, Ludtke R, Selbmann HK, et al. Efficacy and tolerability of a standardized willow bark extract in patients with osteoarthritis: randomized placebo-controlled, double blind clinical trial. Phytother Res 2001;15:344-50. PubMed
    3. 12475. Biegert C, Wagner I, Ludtke R, et al. Efficacy and safety of willow bark extract in the treatment of osteoarthritis and rheumatoid arthritis: results of 2 randomized double-blind controlled trials. J Rheumatol 2004;31:2121-30.
    4. 12804. Chrubasik S, Kunzel O, Model A, et al. Treatment of low back pain with a herbal or synthetic anti-rheumatic: a randomized controlled study. Willow bark extract for low back pain. Rheumatology (Oxford) 2001;40:1388-93. PubMed
    5. 86459. Chrubasik, S., Kunzel, O., Black, A., Conradt, C., and Kerschbaumer, F. Potential economic impact of using a proprietary willow bark extract in outpatient treatment of low back pain: an open non-randomized study. Phytomedicine 2001;8(4):241-251. PubMed

    Tofacitinib

    Listed in the ADVERSE REACTIONS section of the FDA label for Tofacitinib. Read the label on DailyMed ›

Reported for Willow Bark but not commonly for Tofacitinib: bleeding in the gut, kidney problems, a severe allergic reaction and stomach upset.

Effects for Tofacitinib come from the ADVERSE REACTIONS section of its FDA label; effects for Willow Bark come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 185,980 voluntary FDA FAERS reports for Tofacitinib 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

Willow Bark in Pregnancy & Breastfeeding

Lactation Possibly Unsafe

When used orally. Willow bark contains salicylates which are excreted in breast milk and have been linked to adverse effects in breast-fed infants.

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 Tofacitinib Is Prescribed For, and What Willow Bark Has Been Studied For

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

Willow Bark has been studied for:

  • Joint pain studied, not established Willow Bark has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Willow Bark for joint pain

    Oral willow bark has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

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 Tofacitinib on your own; if you are taking Willow Bark for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Tofacitinib

This page covers Willow Bark only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tofacitinib page lists 184 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Active Hexose Correlated Compound (ahcc) (moderate).

By severity: 3 major · 143 moderate · 38 minor.

From our pharmacist’s overview on the Tofacitinib page

“Supplements deserve genuine care alongside tofacitinib (Xeljanz, Xeljanz XR), a medicine that deliberately dials down the immune system to control conditions like rheumatoid arthritis and ulcerative colitis. Most of the interactions on this page run through the liver enzymes that clear the drug, meaning an herb can push its blood level…”

Reviewed by 2 · Jul 18, 2026

Open the Tofacitinib interaction page

One more smart check

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

We hold 43 real supplement products containing Willow Bark, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Willow Bark. Even though Willow Bark itself has no known interaction with Tofacitinib, 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 Willow Bark and Tofacitinib 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 Willow Bark
Steady interest

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

29 days ago today
Medication Tofacitinib
Steady interest

#1,579 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 Willow Bark reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Willow Bark and Tofacitinib records this page draws on were last updated July 11, 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 Willow Bark

What is Willow Bark?

  • Low back pain
  • Osteoarthritis joint pain
  • Headache
  • Fever
  • General aches and inflammation

Willow bark is a traditional plant remedy that contains salicin, a compound related to aspirin, and is most often used for pain and inflammation. Some evidence suggests it may modestly help low back pain and joint pain, but the research is limited and the right dose is not well standardized. Because it acts like aspirin, people with aspirin allergies, bleeding problems, or who are pregnant should be cautious and talk to a pharmacist or doctor first.

Salix alba · Salicaceae · Bark · Capsules, tablets, dried bark for tea, liquid extracts, standardized extracts

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

Willow Bark: dosing

There is no single official dose for willow bark. Products vary widely, and many are standardized to a certain amount of salicin, which is the part researchers usually measure.Because strength differs from brand to brand, the best approach is to follow the directions on the product label and not exceed them. They can help you decide whether willow bark is appropriate and how much is reasonable for you.

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

Read the full Willow Bark monograph & all interactions
Medication

About Tofacitinib

What Is Tofacitinib Used For?

Brand names: Xeljanz, Xeljanz XR

  • Tofacitinib is used alone or with other medications to treat rheumatoid arthritis (condition in which the body attacks its own joints causing pain, swelling, and loss of function) in adults who are unable to take or did not respond to one or more tumor necrosis factor (TNF) inhibitor medication(s). It is also used to treat psoriatic arthritis (a condition that causes joint pain and swelling and scales on the skin) in adults who are unable to take or did not respond to or tolerate one or more TNF inhibitor medication(s). Tofacitinib is used to treat ulcerative colitis (a condition which causes swelling and sores in the lining of the colon [large intestine] and rectum) in adults who are unable to take or who did not respond to one or more TNF inhibitor medication(s). It is also used to treat polyarticular juvenile idiopathic arthritis (PJIA; a type of childhood arthritis that affects five or more joints during the first six months of the condition, causing pain, swelling, and loss of function) in children 2 years and older who are unable to take or who did not respond to one or more TNF inhibitor medication(s). Tofacitinib is in a class of medications called Janus kinase (JAK) inhibitors. It works by decreasing the activity of the immune system.

See full Tofacitinib drug information
Keep checking

Other Drugs & Willow Bark

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

0Major
127Moderate
0Minor
2,702No known interaction
127 Moderate 2,702 No interaction
Moderate

127 interactions

Showing 60 of 127 moderate interactions — see all 127 on the Willow Bark page.

No interaction 2,702 drugs checked — show the list

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

Showing the 60 most looked-up of 2,702 medications checked with no known interaction — see the full Willow Bark list.

See the full Willow Bark interactions page
See every supplement checked against Tofacitinib, ranked by severity
Evidence & sources

Willow Bark References

The 12 references that drive our Willow Bark 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. Chrubasik S, Eisenberg E, Balan E, et al. Treatment of low back pain exacerbations with willow bark extract: a randomized double-blind study. Am J Med 2000;109:9-14. PubMed
  2. Schmid B, Ludtke R, Selbmann HK, et al. Efficacy and tolerability of a standardized willow bark extract in patients with osteoarthritis: randomized placebo-controlled, double blind clinical trial. Phytother Res 2001;15:344-50. PubMed
  3. Biegert C, Wagner I, Ludtke R, et al. Efficacy and safety of willow bark extract in the treatment of osteoarthritis and rheumatoid arthritis: results of 2 randomized double-blind controlled trials. J Rheumatol 2004;31:2121-30.
  4. Unsworth J, d'Assis-Fonseca A, Beswick DT, Blake DR. Serum salicylate levels in a breast fed infant. Ann Rheum Dis 1987;46:638-9. PubMed
  5. Clark JH, Wilson WG. A 16-day-old breast-fed infant with metabolic acidosis caused by salicylate. Clin Pediatr (Phila) 1981;20:53-4. PubMed
  6. Chrubasik S, Kunzel O, Model A, et al. Treatment of low back pain with a herbal or synthetic anti-rheumatic: a randomized controlled study. Willow bark extract for low back pain. Rheumatology (Oxford) 2001;40:1388-93. PubMed
  7. Schmid B, Kotter I, Heide L. Pharmacokinetics of salicin after oral administration of a standardised willow bark extract. Eur J Clin Pharmacol. 2001;57:387-91. PubMed
  8. Krivoy N, Pavlotzky E, Chrubasik S, et al. Effect of salicis cortex extract on human platelet aggregation. Planta Med 2001;67:209-12. PubMed
  9. Mills SY, Jacoby RK, Chacksfield M, Willoughby M. Effect of a proprietary herbal medicine on the relief of chronic arthritic pain: a double-blind study. Br J Rheumatol 1996;35:874-8. PubMed
  10. Chrubasik, S., Kunzel, O., Black, A., Conradt, C., and Kerschbaumer, F. Potential economic impact of using a proprietary willow bark extract in outpatient treatment of low back pain: an open non-randomized study. Phytomedicine 2001;8(4):241-251. PubMed
  11. <p>Moro PA, Flacco V, Cassetti F, Clementi V, Colombo ML, Chiesa GM, Menniti-Ippolito F, Raschetti R, Santuccio C. Hypovolemic shock due to severe gastrointestinal bleeding in a child taking an herbal syrup. Ann Ist Super Sanita. 2011;47(3):278-83.</p>
  12. Sweeney, K. R., Chapron, D. J., Brandt, J. L., Gomolin, I. H., Feig, P. U., and Kramer, P. A. Toxic interaction between acetazolamide and salicylate: case reports and a pharmacokinetic explanation. Clin Pharmacol Ther 1986;40(5):518-524.

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 Willow Bark and Tofacitinib Together: Common Questions

Is it safe to take Willow Bark with Tofacitinib?
We do not list a known interaction between Willow Bark and Tofacitinib. 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 Willow Bark and Tofacitinib have any of the same side effects?
Yes — our sources link each of them separately to 4 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 Willow Bark and Tofacitinib 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 Willow Bark in each. That is a conversation for your prescriber, especially if Tofacitinib is being adjusted to a target.
How was the Willow Bark and Tofacitinib combination checked?
Interactions in our licensed database are recorded against drug classes. Tofacitinib is filed under 4 classifications, and Willow Bark has documented interactions with 5 drug classes — none of Tofacitinib'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 Willow Bark interact with any other medications?
Yes. Willow Bark has 127 documented drug interactions in our database — Tofacitinib 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 Tofacitinib interact with any supplements?
Yes. Tofacitinib has documented interactions with 184 supplements in our database — Willow Bark is not one of them. The Tofacitinib 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

Willow Bark monograph Uses, safety profile, and every drug interaction in one place Tofacitinib drug information The full plain-English guide to this medication Tofacitinib supplement interactions Every supplement checked against Tofacitinib, 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 12 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Tofacitinib and Willow Bark?

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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.