Drug & supplement interaction

Lousewort + Fosamprenavir

Fosamprenavir brand names: Lexiva, Telzir.

No Known Interaction
The bottom line No known interaction

We found no known interaction between Lousewort and Fosamprenavir 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.

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Interaction report

Lousewort and Fosamprenavir

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 Fosamprenavir and Lousewort 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 Lousewort at all — not against Fosamprenavir, 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.

Lousewort safety at a glance

Lousewort overall Not established Human safety data are very limited, and some Pedicularis species may contain potentially toxic alkaloids.
Pregnancy Avoid No reliable safety data exist, so it should be avoided during pregnancy.
Breastfeeding Avoid No safety information is available, so it is best avoided while breastfeeding.

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

Still wondering about combining Fosamprenavir and Lousewort? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Fosamprenavir’s Own FDA Label Lists

This is not an interaction — none of it involves Lousewort. These are the most notable effects listed in the ADVERSE REACTIONS section of Fosamprenavir’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. 5 of them are worth acting on rather than waiting out — marked below.

  • Kidney stones Worth acting on
  • A heart attack Worth acting on
  • High blood sugar Worth acting on
  • A severe allergic reaction Worth acting on
  • A low white blood cell count Worth acting on
  • Numbness or tingling
  • Itching
  • Stomach pain
  • Tiredness
  • Diarrhea

Showing the 10 most notable of 14 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 Fosamprenavir. Read the label on DailyMed › Lousewort’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Lousewort side to compare — that is a limit of the record, not a statement that Lousewort has no side effects.

Everything else you take

See Every Supplement That Interacts With Fosamprenavir

This page covers Lousewort only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosamprenavir page lists 143 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 Adrafinil (moderate).

By severity: 3 major · 100 moderate · 40 minor.

From our pharmacist’s overview on the Fosamprenavir page

“Fosamprenavir (Lexiva, Telzir) keeps HIV suppressed only if its blood level stays where it belongs, so the 143 supplement interactions on file deserve real attention, not a shrug. Three are rated major and those are the ones to understand first.”

Reviewed by 2 · Jul 18, 2026

Open the Fosamprenavir interaction page

How much people look this up

Where Lousewort and Fosamprenavir 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 Lousewort
Steady interest

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

29 days ago today
Medication Fosamprenavir
Top half

#1,374 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. Lousewort is not yet covered by that licensed database, so its write-up cites publicly available medical sources directly (see the references below).
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Lousewort reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Lousewort and Fosamprenavir records this page draws on were last updated June 22, 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 Lousewort

What is Lousewort?

  • Muscle relaxation
  • Sleep and relaxation
  • Mild pain relief
  • Stress and tension

Lousewort refers to several plants in the Pedicularis genus, traditionally used as a mild muscle relaxant and calming herb. There is very little scientific research on its safety or effectiveness in humans, and some species may contain toxic compounds, so caution is strongly advised.

Pedicularis spp. · Orobanchaceae · Aerial parts (flowers, leaves, and stems) · Tea, tincture, dried herb, capsules, smoking blends

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

Lousewort: dosing

There is no established standard dose for lousewort. Traditional use varies widely, and no clinical studies have determined a safe or effective amount.If you choose to use a product, follow the directions on the label and start with the lowest suggested amount.

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

Read the full Lousewort monograph & all interactions
Medication

About Fosamprenavir

What Is Fosamprenavir Used For?

Brand names: Lexiva, Telzir

Fosamprenavir tablets (sold as Fosamprenavir Calcium and Lexiva) are used together with other antiretroviral medicines to treat HIV-1 infection in adults and in children as young as 4 weeks old. It is not used alone — it is always part of a combination regimen.

For adults who have already taken protease inhibitor medicines before, fosamprenavir is used alongside a low dose of ritonavir. Once-daily dosing with ritonavir is not recommended for adults who have previously used protease inhibitors, or for any pediatric patients.

See full Fosamprenavir drug information
Keep checking

Other Drugs & Lousewort

Browse every other medication we’ve checked against Lousewort — 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
No interaction 2,829 drugs checked — show the list
Evidence & sources

Lousewort References

The 1 sources that drive our Lousewort monograph — publicly available pages from reputable medical and government organizations. Every link was verified to work before publishing. Lousewort is not covered by the licensed Natural Medicines interaction database, so its page cites these public sources directly.

  1. Using Dietary Supplements Wisely — NIH NCCIH Source

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 Lousewort and Fosamprenavir Together: Common Questions

Is it safe to take Lousewort with Fosamprenavir?
We do not list a known interaction between Lousewort and Fosamprenavir. 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.
Does Fosamprenavir interact with any supplements?
Yes. Fosamprenavir has documented interactions with 143 supplements in our database — Lousewort is not one of them. The Fosamprenavir interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Fosamprenavir and Lousewort?

Our pharmacists answer your medication & supplement questions — free.

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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.