Drug & supplement interaction

Masterwort + Cobicistat

Cobicistat brand name: Tybost.

No Known Interaction
Medically reviewed by · Updated June 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Masterwort and Cobicistat 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 label for Cobicistat states a food rule worth keeping to.

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Interaction report

Masterwort and Cobicistat

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 Cobicistat and Masterwort 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.

Masterwort safety at a glance

Masterwort overall Use caution Limited safety data exist, and the plant can cause sun-triggered skin reactions.
Pregnancy Avoid Not enough safety information; best avoided during pregnancy.
Breastfeeding Avoid No reliable safety data, so avoid while breastfeeding.

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

Still wondering about combining Cobicistat and Masterwort? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Cobicistat

Interactions in our licensed database are recorded against drug classes, not just single drug names. Cobicistat is filed under 2 classifications — cytochrome p450 3a4 (cyp3a4) inhibitors, oral drugs. Masterwort has documented interactions with 1 drug class — the most serious being photosensitizing drugs (moderate) — and none of Cobicistat’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

Masterwort Does Interact With Other Medications

Masterwort has 335 moderate known drug interactions in our database — Cobicistat isn’t one of them. If you take anything else, check it against the full list below.

Moderate 335 No known interaction 2,495 (incl. Cobicistat)
Taking anything else?

Check Another of Your Medications Against Masterwort

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

What to actually watch for

What Cobicistat’s Own FDA Label Lists

This is not an interaction — none of it involves Masterwort. These are the most notable effects listed in the ADVERSE REACTIONS section of Cobicistat’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. 7 of them are worth acting on rather than waiting out — marked below.

  • Kidney problems Worth acting on mentioned in 44.9% of FDA reports for Cobicistat
  • Kidney stones Worth acting on
  • Severe muscle breakdown Worth acting on
  • Yellowing of the skin or eyes Worth acting on
  • Low mood Worth acting on
  • Hives Worth acting on
  • An allergic reaction Worth acting on
  • Vivid dreams or nightmares
  • Trouble sleeping
  • Itching

Showing the 10 most notable of 17 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 Cobicistat. Read the label on DailyMed › Where a percentage is shown, it is the share of 20,779 voluntary FDA FAERS reports for Cobicistat that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Masterwort’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Masterwort side to compare — that is a limit of the record, not a statement that Masterwort has no side effects.

How to take them

Some Cobicistat Products Have a Food Rule — Masterwort Should Not Break It

At least one FDA label for a product containing Cobicistat says to take it with food. If you take Masterwort on an empty stomach out of habit, keep them separate — and take Cobicistat with a meal where the label says to.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Cobicistat products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

2 DOSAGE AND ADMINISTRATION TYBOST must be coadministered with atazanavir or darunavir at the same time, with food, and in combination with other HIV-1 antiretroviral agents.

From the Dosage and Administration section of the FDA label we read for Cobicistat — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

Everything else you take

See Every Supplement That Interacts With Cobicistat

This page covers Masterwort only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Cobicistat page lists 30 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Adrafinil (moderate), Cannabidiol (cbd) (moderate), Cannabinol (cbn) (moderate) and Cannabis (moderate).

By severity: 1 major · 19 moderate · 10 minor.

From our pharmacist’s overview on the Cobicistat page

“Activated charcoal is the one entry to understand first if you take cobicistat (Tybost). Charcoal soaks up drugs in the gut, and since cobicistat's entire job is boosting an HIV medicine to protective levels, blunting its absorption can put the whole regimen at risk.”

Reviewed by 2 · Jul 18, 2026

Open the Cobicistat interaction page

How much people look this up

Where Masterwort and Cobicistat 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 Masterwort
Top half

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

29 days ago today
Medication Cobicistat
Steady interest

#2,335 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 Masterwort reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Masterwort and Cobicistat records this page draws on were last updated June 20, 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 Masterwort

What is Masterwort?

Masterwort
  • Digestive upset
  • Mild anxiety and tension
  • Skin complaints
  • Respiratory and cough relief
  • Traditional tonic

Masterwort (Heracleum sphondylium), a plant in the carrot family, has a long folk-medicine history for digestion, nerves, and skin. Modern scientific evidence to support these uses is very limited, and the plant can cause skin reactions to sunlight, so use it cautiously and talk with your pharmacist or doctor first.

Heracleum sphondylium · Apiaceae · Root, leaves, seeds, and aerial parts · Tea, tincture, dried herb, essential oil

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

Masterwort: dosing

There is no standardized, well-established dose for masterwort. Traditional preparations vary widely, and product strengths are not consistent.If you choose to use a commercial product, follow the directions on the label and do not exceed the suggested amount.

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

Read the full Masterwort monograph & all interactions
Medication

About Cobicistat

What Is Cobicistat Used For?

Brand name: Tybost

Tybost (cobicistat) is not itself an HIV treatment — it works by slowing the breakdown of certain HIV medicines so they stay active in your body long enough to work. Specifically, Tybost is used to boost the HIV medicines atazanavir or darunavir (once-daily dosing) as part of a complete HIV-1 treatment regimen in adults and in children weighing at least 14 kg (about 31 lbs).

Tybost is not interchangeable with ritonavir (another booster) for all HIV medicines. It is not recommended with darunavir twice-daily, fosamprenavir, saquinavir, or tipranavir.

Most-Reported Side Effects for Cobicistat

From FAERS, the FDA’s public side-effect reporting system (20,779 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Bone density decreased 8,112 reports
Chronic kidney disease 4,754 reports
Renal injury 4,577 reports
Tooth loss 4,186 reports
Bone loss 4,107 reports
See full Cobicistat drug information
Keep checking

Other Drugs & Masterwort

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

0Major
335Moderate
0Minor
2,494No known interaction
335 Moderate 2,494 No interaction
Moderate

335 interactions

Showing 60 of 335 moderate interactions — see all 335 on the Masterwort page.

No interaction 2,494 drugs checked — show the list

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

Showing the 60 most looked-up of 2,494 medications checked with no known interaction — see the full Masterwort list.

See the full Masterwort interactions page
See every supplement checked against Cobicistat, ranked by severity
Evidence & sources

Masterwort References

The 1 references that drive our Masterwort 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. 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 Masterwort and Cobicistat Together: Common Questions

Is it safe to take Masterwort with Cobicistat?
We do not list a known interaction between Masterwort and Cobicistat. 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.
Should I take Masterwort and Cobicistat at the same time of day?
At least one FDA label for a product containing Cobicistat says to take it with food. If you take Masterwort on an empty stomach out of habit, keep them separate and take Cobicistat with a meal where the label says to. Food instructions belong to the product rather than the ingredient — two Cobicistat products can differ — so check the directions on your own box. This is about absorption, not an interaction.
How was the Masterwort and Cobicistat combination checked?
Interactions in our licensed database are recorded against drug classes. Cobicistat is filed under 2 classifications, and Masterwort has documented interactions with 1 drug class — none of Cobicistat'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 Masterwort interact with any other medications?
Yes. Masterwort has 335 documented drug interactions in our database — Cobicistat 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 Cobicistat interact with any supplements?
Yes. Cobicistat has documented interactions with 30 supplements in our database — Masterwort is not one of them. The Cobicistat 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

Masterwort monograph Uses, safety profile, and every drug interaction in one place Cobicistat drug information The full plain-English guide to this medication Cobicistat supplement interactions Every supplement checked against Cobicistat, 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 1 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Cobicistat and Masterwort?

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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.