Drug & supplement interaction

Blessed Thistle + Fostemsavir Tromethamine

Fostemsavir Tromethamine brand name: Rukobia.

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 Blessed Thistle and Fostemsavir Tromethamine 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

Blessed Thistle and Fostemsavir Tromethamine

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 Fostemsavir Tromethamine and Blessed Thistle 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.

Blessed Thistle safety at a glance

Blessed Thistle overall Use caution Often well tolerated in small amounts, but human safety data are limited and large doses can cause nausea or vomiting.
Pregnancy Likely Unsafe When used orally; avoid using. Read the full pregnancy detail
Breastfeeding Use caution Used traditionally to support milk supply, but safety has not been well studied, so check with your doctor first.

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 Fostemsavir Tromethamine and Blessed Thistle? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Fostemsavir Tromethamine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Fostemsavir Tromethamine is filed under 3 classifications — qt interval-prolonging drugs, cytochrome p450 3a4 (cyp3a4) substrates, oral drugs. Blessed Thistle has documented interactions with 3 drug classes — the most serious being antacids (minor), h2-blockers (minor) and proton pump inhibitors (ppis) (minor) — and none of Fostemsavir Tromethamine’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

Blessed Thistle Does Interact With Other Medications

Blessed Thistle has 36 minor known drug interactions in our database — Fostemsavir Tromethamine isn’t one of them. If you take anything else, check it against the full list below.

Minor 36 No known interaction 2,794 (incl. Fostemsavir Tromethamine)
Taking anything else?

Check Another of Your Medications Against Blessed Thistle

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

What to actually watch for

No Interaction Found — But Data Suggests Blessed Thistle and Fostemsavir Tromethamine 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.

  • Stomach upset / Vomiting Additional detail

    Blessed Thistle

    “Orally, when blessed thistle is used in doses higher than 5 grams per cup of tea, it can cause stomach irritation and vomiting (12).”

    Blessed Thistle · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.

    Fostemsavir Tromethamine

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

  • A skin rash reported in 4.6% of FDA reports for Fostemsavir Tromethamine Additional detail

    Blessed Thistle

    “Topically, blessed thistle can cause an allergic reaction, such as dermatitis, in individuals sensitive to the Asteraceae/Compositae family. Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many other herbs (12).”

    Blessed Thistle · Natural Medicines adverse-effect record, reported in dermatitis.

    1 source cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.

    Fostemsavir Tromethamine

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

Reported for Blessed Thistle but not commonly for Fostemsavir Tromethamine: an allergic reaction.

Effects for Fostemsavir Tromethamine come from the ADVERSE REACTIONS section of its FDA label; effects for Blessed Thistle come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 238 voluntary FDA FAERS reports for Fostemsavir Tromethamine 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

Blessed Thistle in Pregnancy & Breastfeeding

Pregnancy 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 Fostemsavir Tromethamine

This page covers Blessed Thistle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fostemsavir Tromethamine page lists 146 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Cesium (major) and Ephedra (major).

By severity: 8 major · 98 moderate · 40 minor.

Open the Fostemsavir Tromethamine interaction page

One more smart check

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

We hold 729 real supplement products containing Blessed Thistle, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Blessed Thistle. Even though Blessed Thistle itself has no known interaction with Fostemsavir Tromethamine, 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 Blessed Thistle and Fostemsavir Tromethamine 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 Blessed Thistle
Top 25%

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

29 days ago today
Medication Fostemsavir Tromethamine
Top half

#1,384 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 Blessed Thistle reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Blessed Thistle and Fostemsavir Tromethamine 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 Blessed Thistle

What is Blessed Thistle?

Blessed Thistle
  • Digestive upset and poor appetite
  • Boosting bile flow
  • General bitter tonic
  • Supporting milk supply during breastfeeding (traditional)
  • Wound care (traditional, topical)

Blessed thistle is a bitter herb traditionally used to stimulate appetite and ease mild digestive complaints. High-quality human studies are lacking, so its benefits are not well proven. It is likely fine for short-term use in small, food-like amounts, but it should be avoided in pregnancy and used with caution by people allergic to ragweed and related plants.

Cnicus benedictus · Asteraceae · Aerial parts (leaves, stems, and flowers) · Tea, tincture, liquid extract, capsules, dried herb

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

Blessed Thistle: dosing

There is no official, standardized dose of blessed thistle. The right amount can vary depending on the product and the form (tea, tincture, or capsules).The best approach is to follow the directions on the product label and not exceed the recommended amount, since large doses are more likely to cause nausea and vomiting.

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

Read the full Blessed Thistle monograph & all interactions
Medication

About Fostemsavir

What Is Fostemsavir Used For?

Brand name: Rukobia

Rukobia (fostemsavir) is used to treat HIV-1 infection in adults who have tried many other antiretroviral treatments and whose virus is no longer responding — due to resistance, side effects, or safety concerns. It is always used alongside other HIV medicines, not on its own.

Rukobia is specifically intended for heavily treatment-experienced patients with multidrug-resistant HIV-1 who are failing their current regimen. It is not a first-line HIV treatment.

Most-Reported Side Effects for Fostemsavir Tromethamine

From FAERS, the FDA’s public side-effect reporting system (238 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Nausea 17 reports
Rash 11 reports
Viral load increased 11 reports
Pathogen resistance 10 reports
Dizziness 9 reports
See full Fostemsavir drug information
Keep checking

Other Drugs & Blessed Thistle

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

0Major
0Moderate
36Minor
2,793No known interaction
36 Minor 2,793 No interaction
Minor

36 interactions

No interaction 2,793 drugs checked — show the list

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

Showing the 60 most looked-up of 2,793 medications checked with no known interaction — see the full Blessed Thistle list.

See the full Blessed Thistle interactions page
See every supplement checked against Fostemsavir Tromethamine, ranked by severity
Evidence & sources

Blessed Thistle References

The 2 references that drive our Blessed Thistle 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. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

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 Blessed Thistle and Fostemsavir Tromethamine Together: Common Questions

Is it safe to take Blessed Thistle with Fostemsavir Tromethamine?
We do not list a known interaction between Blessed Thistle and Fostemsavir Tromethamine. 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 Blessed Thistle and Fostemsavir Tromethamine have any of the same side effects?
Yes — our sources link each of them separately to 3 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.
How was the Blessed Thistle and Fostemsavir Tromethamine combination checked?
Interactions in our licensed database are recorded against drug classes. Fostemsavir Tromethamine is filed under 3 classifications, and Blessed Thistle has documented interactions with 3 drug classes — none of Fostemsavir Tromethamine'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 Blessed Thistle interact with any other medications?
Yes. Blessed Thistle has 36 documented drug interactions in our database — Fostemsavir Tromethamine 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 Fostemsavir Tromethamine interact with any supplements?
Yes. Fostemsavir Tromethamine has documented interactions with 146 supplements in our database — Blessed Thistle is not one of them. The Fostemsavir Tromethamine 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

Blessed Thistle monograph Uses, safety profile, and every drug interaction in one place Fostemsavir drug information The full plain-English guide to this medication Fostemsavir Tromethamine supplement interactions Every supplement checked against Fostemsavir Tromethamine, 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 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Fostemsavir Tromethamine and Blessed Thistle?

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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.