Drug & supplement interaction

Baikal Skullcap + Saquinavir

Saquinavir brand names: Invirase, Fortovase.

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

Saquinavir falls into 2 drug categories that Baikal Skullcap can interact with; the most serious is rated minor. Theoretically, Baikal skullcap might increase levels of drugs transported by P-glycoprotein.

Read the full interaction report
SeverityMinor
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Baikal Skullcap and Saquinavir

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Baikal Skullcap interacts with whole categories of medication. Saquinavir falls into 2 of those categories, so it can interact with Baikal Skullcap in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Minor).

Minor

P-GLYCOPROTEIN SUBSTRATES

1 of 2

Why this applies to Saquinavir

Saquinavir falls under P-GLYCOPROTEIN SUBSTRATES — the group Baikal Skullcap interacts with.

Theoretically, Baikal skullcap might increase levels of drugs transported by P-glycoprotein.
In vitro and animal research suggests that baicalein, oroxylin A, and wogonin, constituents of Baikal skullcap, can inhibit P-glycoprotein. This effect has not been reported in humans.
Severity Minor Likelihood Possible Evidence D

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 gist if you take Baikal skullcap alongside saquinavir. Your body uses a kind of cellular pump called P-glycoprotein to move saquinavir around and push some of it back out. In test tube and animal studies, certain compounds in this herb (baicalein and wogonin) seemed to slow that pump down a bit. If that happened in people, a little more saquinavir could stay in your system, which could mean stronger effects or more of its usual side effects like nausea, diarrhea, belly upset, or headache.

The honest truth: this has only been seen in the lab, never confirmed in humans, and it's rated minor. Still, since saquinavir is an important HIV medicine, I'd run any supplement past your pharmacist or doctor first rather than guessing.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Lee, Y., Yeo, H., Liu, S. H., Jiang, Z., Savizky, R. M., Austin, D. J., and Cheng, Y. C. Increased anti-P-glycoprotein activity of baicalein by alkylation on the A ring. J Med Chem 10-21-2004;47(22):5555-5566. PubMed
  2. Lee, E., Enomoto, R., Suzuki, C., Ohno, M., Ohashi, T., Miyauchi, A., Tanimoto, E., Maeda, K., Hirano, H., Yokoi, T., and Sugahara, C. Wogonin, a plant flavone, potentiates etoposide-induced apoptosis in cancer cells. Ann N Y Acad Sci 2007;1095:521-526. PubMed
  3. Go, W. J., Ryu, J. H., Qiang, F., and Han, H. K. Evaluation of the flavonoid oroxylin A as an inhibitor of P-glycoprotein-mediated cellular efflux. J Nat Prod 2009;72(9):1616-1619. PubMed
  4. Enomoto, R., Koshiba, C., Suzuki, C., and Lee, E. Wogonin potentiates the antitumor action of etoposide and ameliorates its adverse effects. Cancer Chemother.Pharmacol 2011;67(5):1063-1072. PubMed
Minor

ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP)

2 of 2

Saquinavir also falls under ORGANIC ANION-TRANSPORTING POLYPEPTIDE SUBSTRATES (OATP).

Theoretically, Baikal skullcap might alter the levels and clinical effects of OATP substrates.
Some pharmacokinetic research shows that baicalin, a constituent of Baikal skullcap, can decrease plasma levels of rosuvastatin. The mechanism is thought to involve stimulation of the activity of the organic anion-transporting polypeptide 1B1 (OATP1B1), which transports rosuvastatin into the liver. This decreases plasma levels of the drug, but increases levels at the site of action in the liver. The degree to which rosuvastatin levels are affected depends on the OATP1B1 haplotype of the individual. Baikal skullcap might also affect other OATP1B1 substrates.
Severity Minor 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 situation with Baikal skullcap and saquinavir (Invirase). Saquinavir is moved around the body partly by liver transporters called OATPs. Lab and some early human research suggests one compound in skullcap, baicalin, may rev up an OATP transporter (OATP1B1) that pulls certain drugs into the liver. In theory, that could nudge saquinavir levels in your blood down a bit.

I want to be honest about how soft this evidence is. It's rated minor, and most of what we know comes from a different drug (rosuvastatin), not saquinavir itself. Still, with an HIV medication you really don't want unexpected dips, since lower levels could mean less control of the virus. Please don't change anything on your own. Just run this past your HIV pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Fan L, Zhang W, Guo D, et al. The effect of herbal medicine baicalin on pharmacokinetics of rosuvastatin, substrate of organic anion-transporting polypeptide 1B1. Clin Pharmacol Ther 2007;83:471-6. PubMed
  2. Chen C, Mireles RJ, Campbell SD, et al. Differential interaction of 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors with ABCB1, ABCC2, and OATP1B1. Drug Metab Dispos 2005;33:537-46. PubMed
  3. Pasanen MK, Fredrikson H, Neuvonen PJ, Niemi M. Different effects of SLCO1B1 polymorphism on the pharmacokinetics of atorvastatin and rosuvastatin. Clin Pharmacol Ther 2007;82:726-33. PubMed
  4. Konig J, Seithel A, Gradhand U, Fromm MF. Pharmacogenomics of human OATP transporters. Naunyn-Schmiedeberg Arch Pharmacol 2006;372:432-43. PubMed

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

Baikal Skullcap Also Interacts With Other Medications

Baikal Skullcap has 594 moderate, 351 minor known drug interactions in our database — the Saquinavir one above is among them. If you take anything else, check it against the full list below.

Moderate 594 Minor 351 No known interaction 1,885 (incl. Saquinavir)
Taking anything else?

Check Another of Your Medications Against Baikal Skullcap

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

From our Q&A

Questions About Baikal Skullcap or Saquinavir

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Baikal Skullcap or Saquinavir, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Saquinavir

This page covers Baikal Skullcap only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Saquinavir page lists 175 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Apple (major), Grapefruit (major), St. John's Wort (major) and Sweet Orange (major).

By severity: 5 major · 130 moderate · 40 minor.

From our pharmacist’s overview on the Saquinavir page

“Saquinavir (Invirase), a protease inhibitor for HIV, only works while its blood level stays steady, which makes this a list to read carefully rather than skim. Five of the 175 ingredients carry a major rating, and several are ordinary drinks.”

Reviewed by 2 · Jul 18, 2026

Open the Saquinavir interaction page

One more smart check

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

We hold 737 real supplement products containing Baikal Skullcap, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Baikal Skullcap. Your product may carry other ingredients that interact with Saquinavir too, on top of Baikal Skullcap — 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 Baikal Skullcap and Saquinavir 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 Baikal Skullcap
Top 25%

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

29 days ago today
Medication Saquinavir
Top half

#743 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 Baikal Skullcap

What is Baikal Skullcap?

Baikal Skullcap
  • Inflammation
  • Allergies
  • Anxiety and sleep
  • Immune support
  • Respiratory infections

Baikal skullcap is a traditional Chinese herb (Huang Qin) used for inflammation, allergies, and infections, with active compounds like baicalin and baicalein studied mostly in the lab. Human evidence remains limited, so it should not replace proven treatments. Talk to your pharmacist or doctor before using it, and avoid it in pregnancy and breastfeeding.

Read the full Baikal Skullcap monograph & all interactions
Medication

About Saquinavir

What Is Saquinavir Used For?

Brand names: Invirase, Fortovase

  • Saquinavir is used in combination with ritonavir (Norvir) and other medications to treat human immunodeficiency virus (HIV) infection. Saquinavir is in a class of medications called protease inhibitors. It works by decreasing the amount of HIV in the blood. Although saquinavir does not cure HIV, it may decrease your chance of developing acquired immunodeficiency syndrome (AIDS) and HIV-related illnesses such as serious infections or cancer. Taking these medications along with practicing safer sex and making other lifestyle changes may decrease the risk of transmitting the HIV virus to other people.

See full Saquinavir drug information
Keep checking

Other Drugs & Baikal Skullcap

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

0Major
594Moderate
351Minor
1,884No known interaction
594 Moderate 351 Minor 1,884 No interaction
Moderate

594 interactions

Showing 60 of 594 moderate interactions — see all 594 on the Baikal Skullcap page.

Minor

351 interactions

Showing 60 of 351 minor interactions — see all 351 on the Baikal Skullcap page.

No interaction 1,884 drugs checked — show the list

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

Showing the 60 most looked-up of 1,884 medications checked with no known interaction — see the full Baikal Skullcap list.

See the full Baikal Skullcap interactions page
See every supplement checked against Saquinavir, 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
Baikal Skullcap monograph › Uses, safety, and every drug interaction in one place Saquinavir supplement interactions › Every supplement checked against Saquinavir, ranked by severity Saquinavir 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 Baikal Skullcap and Saquinavir Together: Common Questions

Can you take Baikal Skullcap with Saquinavir?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Baikal Skullcap and Saquinavir?
Saquinavir belongs to more than one drug category, and Baikal Skullcap interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Baikal Skullcap and Saquinavir interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Saquinavir and Baikal Skullcap?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.