Drug & supplement interaction

Khella + Fostamatinib

Fostamatinib brand name: Tavalisse.

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

Khella has a moderate interaction with Fostamatinib. Theoretically, khella might have additive adverse effects on the liver when used with hepatotoxic drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Khella and Fostamatinib

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

Moderate

HEPATOTOXIC DRUGS

Why this applies to Fostamatinib

Fostamatinib falls under HEPATOTOXIC DRUGS — the group Khella interacts with.

Theoretically, khella might have additive adverse effects on the liver when used with hepatotoxic drugs. Khella can increase liver transaminases. Some drugs that can adversely affect the liver include acetaminophen (Tylenol), amiodarone (Cordarone), carbamazepine (Tegretol), isoniazid (INH), methotrexate (Rheumatrex), methyldopa (Aldomet), and many others.
Severity Moderate Likelihood Possible Evidence B

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 concern with pairing khella and Fostamatinib (Tavalisse). Fostamatinib already has a known habit of raising liver enzymes (your AST and ALT) in some people, which is why your doctor checks bloodwork regularly while you're on it. Khella has been reported to bump those same liver enzymes up. So the worry is simple: using both together could stack one liver stress on top of another.

To be fair, this is mostly a theoretical additive effect rather than a proven, well-studied collision, so I don't want to alarm you. But because liver monitoring is already part of Fostamatinib treatment, it's smart to loop in your pharmacist or doctor before adding khella. Watch for things like belly pain, dark urine, yellowing skin or eyes, or unusual tiredness, and report them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  2. Harvengt C, Desager JP. HDL-cholesterol increase in normolipaemic subjects on khellin: a pilot study. Int J Clin Pharmacol Res 1983;3:363-6.

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

Khella Also Interacts With Other Medications

Khella has 617 moderate known drug interactions in our database — the Fostamatinib one above is one of them. If you take anything else, check it against the full list below.

Moderate 617 No known interaction 2,213 (incl. Fostamatinib)
Taking anything else?

Check Another of Your Medications Against Khella

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

Everything else you take

See Every Supplement That Interacts With Fostamatinib

This page covers Khella only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fostamatinib page lists 209 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Grapefruit (major), Siberian Cocklebur (major) and St. John's Wort (major).

By severity: 6 major · 167 moderate · 36 minor.

From our pharmacist’s overview on the Fostamatinib page

“I would treat the supplement list for fostamatinib (Tavalisse), a medicine that raises platelet counts in chronic immune thrombocytopenia, with real care. Most of what shows up here involves CYP3A4, the liver enzyme that clears fostamatinib, so grapefruit can drive its blood level up while St.”

Reviewed by 2 · Jul 18, 2026

Open the Fostamatinib interaction page

One more smart check

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

We hold 43 real supplement products containing Khella, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Khella. Your product may carry other ingredients that interact with Fostamatinib too, on top of Khella — 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 Khella and Fostamatinib 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 Khella
Steady interest

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

29 days ago today
Medication Fostamatinib
Steady interest

#1,873 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 Khella

What is Khella?

Khella
  • Asthma and bronchitis
  • Angina and heart-related chest pain
  • Kidney stones
  • Vitiligo and psoriasis
  • Mild high blood pressure

Khella is a Mediterranean herb whose seeds contain compounds like khellin that may relax smooth muscle in the airways and blood vessels. While it has a long history of traditional use for breathing and heart problems, modern evidence in supplement form is limited, and it can cause side effects and sun sensitivity, so talk with your pharmacist or doctor before using it.

Read the full Khella monograph & all interactions
Medication

About Fostamatinib

What Is Fostamatinib Used For?

Brand name: Tavalisse

Tavalisse (fostamatinib) is used to treat thrombocytopenia — dangerously low platelet counts — in adults with chronic immune thrombocytopenia (ITP). It is specifically for people whose platelet counts have not improved enough with at least one earlier ITP treatment.

The goal is to raise platelet counts high enough to reduce the risk of serious bleeding. If platelet counts do not respond sufficiently after 12 weeks, the medication is typically stopped.

See full Fostamatinib drug information
Keep checking

Other Drugs & Khella

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

0Major
617Moderate
0Minor
2,212No known interaction
617 Moderate 2,212 No interaction
Moderate

617 interactions

Showing 60 of 617 moderate interactions — see all 617 on the Khella page.

No interaction 2,212 drugs checked — show the list

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

Showing the 60 most looked-up of 2,212 medications checked with no known interaction — see the full Khella list.

See the full Khella interactions page
See every supplement checked against Fostamatinib, 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
Khella monograph › Uses, safety, and every drug interaction in one place Fostamatinib supplement interactions › Every supplement checked against Fostamatinib, ranked by severity Fostamatinib drug information › The full plain-English guide to this medication 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 Khella and Fostamatinib Together: Common Questions

Can you take Khella with Fostamatinib?
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 Khella and Fostamatinib 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 Fostamatinib and Khella?

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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.