Drug & supplement interaction

Mercury Herb + 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 Mercury Herb 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

Mercury Herb 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 Mercury Herb 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 Mercury Herb at all — not against Tofacitinib, 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.

Mercury Herb safety at a glance

Mercury Herb overall Avoid The plant is considered potentially toxic and has poorly defined safe doses.
Pregnancy Likely Unsafe When used orally; avoid using. Read the full pregnancy detail
Breastfeeding Likely 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 Tofacitinib and Mercury Herb? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Mercury Herb 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

    Mercury Herb

    “Orally, mercury herb might cause diarrhea and overactive bladder (18). Symptoms of poisoning might include nerve paralysis, liver and kidney failure, and death (18). The pollen has shown to be allergenic, and may be responsible for rhinitis and asthmatic symptoms.”

    Mercury Herb · Natural Medicines adverse-effect record, reported in diarrhea.

    3 sources cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
    2. 4143. Vallverdu A, Garcia-Ortega P, Martinez J, et al. Mercurialis annua: characterization of main allergens and cross- reactivity with other species. Int Arch Allergy Immunol 1997;112:356-64. PubMed
    3. 4144. Garcia-Ortega P, Martinez J, Martinez A, et al. Mercurialis annua pollen: a new source of allergic sensitization and respiratory disease. J Allergy Clin Immunol 1992;89:987-93.

    Tofacitinib

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

  • Diarrhea Additional detail

    Mercury Herb

    “Orally, mercury herb might cause diarrhea (18).”

    Mercury Herb · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Tofacitinib

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

Reported for Mercury Herb but not commonly for Tofacitinib: kidney problems and a stuffy or runny nose.

Effects for Tofacitinib come from the ADVERSE REACTIONS section of its FDA label; effects for Mercury Herb 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

Mercury Herb in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely 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

Everything else you take

See Every Supplement That Interacts With Tofacitinib

This page covers Mercury Herb 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

How much people look this up

Where Mercury Herb 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 Mercury Herb
Steady interest

#1,335 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Tofacitinib
Top half

#975 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 Mercury Herb reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Mercury Herb and Tofacitinib 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 Mercury Herb

What is Mercury Herb?

  • Constipation
  • Mild skin irritation
  • Swelling or inflammation (topical)
  • Traditional folk remedy

Mercury Herb (Mercurialis annua) is a traditional European plant once used as a mild laxative and topical remedy, but it has very little modern scientific support and is considered potentially toxic. Because the plant can cause serious poisoning when misused, most herbal experts no longer recommend it, and you should talk to a pharmacist or doctor before considering it.

Mercurialis annua · Euphorbiaceae · Leaves and aerial (above-ground) parts · Dried herb, tea/infusion, poultice, traditional topical preparations

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

Mercury Herb: dosing

There is no established or standardized safe dose for Mercury Herb. Because of its toxicity concerns and the lack of modern research, no reliable amount can be recommended.We do not provide specific dosing for this plant. In most cases, safer and better-studied options are available for constipation and skin concerns.

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

Read the full Mercury Herb 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 & Mercury Herb

Browse every other medication we’ve checked against Mercury Herb — 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
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Mercury Herb list.

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

Mercury Herb References

The 3 references that drive our Mercury Herb 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. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  2. Vallverdu A, Garcia-Ortega P, Martinez J, et al. Mercurialis annua: characterization of main allergens and cross- reactivity with other species. Int Arch Allergy Immunol 1997;112:356-64. PubMed
  3. Garcia-Ortega P, Martinez J, Martinez A, et al. Mercurialis annua pollen: a new source of allergic sensitization and respiratory disease. J Allergy Clin Immunol 1992;89:987-93.

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 Mercury Herb and Tofacitinib Together: Common Questions

Is it safe to take Mercury Herb with Tofacitinib?
We do not list a known interaction between Mercury Herb 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 Mercury Herb and Tofacitinib 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.
Does Tofacitinib interact with any supplements?
Yes. Tofacitinib has documented interactions with 184 supplements in our database — Mercury Herb 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

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

Still Have a Question About Tofacitinib and Mercury Herb?

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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.