Drug & supplement interaction

Costus + Ethosuximide

Ethosuximide brand name: Zarontin.

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 Costus and Ethosuximide 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

Costus and Ethosuximide

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 Ethosuximide and Costus 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 Costus at all — not against Ethosuximide, 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.

Costus safety at a glance

Costus overall Use caution Human safety data are limited, and quality and purity of products vary widely.
Pregnancy Avoid Traditionally believed to stimulate the uterus, so it is best avoided during pregnancy.
Breastfeeding Avoid There is not enough safety information, so avoid use while breastfeeding.

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

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

No Interaction Found — But Data Suggests Costus and Ethosuximide May Share a Side Effect

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. One of them is worth acting on rather than waiting out — marked below.

  • An allergic reaction Worth acting on Additional detail

    Costus

    “Orally and topically, costus might cause allergic reactions, including contact dermatitis (11,73140,73155,73281,73284,73288).”

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

    6 sources cited
    1. 11. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
    2. 73140. Marzulli, F. N. and Maibach, H. I. Effects of vehicles and elicitation concentration in contact dermatitis testing. I. Experimental contact sensitization in humans. Contact Dermatitis 1976;2(6):325-329. PubMed
    3. 73155. Mitchell, J. C. Contact hypersensitivity to some perfume materials. Contact Dermatitis 1975;1(4):196-199. PubMed
    4. 73281. Benezra, C. and Epstein, W. L. Molecular recognition patterns of sesquiterpene lactones in costus-sensitive patients. Contact Dermatitis 1986;15(4):223-230. PubMed
    5. 73284. Mitchell, J. C. and Epstein, W. L. Contact hypersensitivity to a perfume material, Costus Absolute. The role of sesquiterpene lactones. Arch.Dermatol 1974;110(6):871-873. DOI
    6. 73288. Cheminat, A., Stampf, J. L., Benezra, C., Farrall, M. J., and Frechet, J. M. Allergic contact dermatitis to costus: removal of haptens with polymers. Acta Derm.Venereol. 1981;61(6):525-529. DOI

    Ethosuximide

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

Reported for Costus but not commonly for Ethosuximide: a skin rash.

Effects for Ethosuximide come from the ADVERSE REACTIONS section of its FDA label; effects for Costus come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 2,490 voluntary FDA FAERS reports for Ethosuximide 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.

Everything else you take

See Every Supplement That Interacts With Ethosuximide

This page covers Costus only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ethosuximide page lists 226 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Grapefruit (major).

By severity: 9 major · 179 moderate · 38 minor.

From our pharmacist’s overview on the Ethosuximide page

“Ethosuximide (Zarontin) prevents absence seizures, and a steady blood level is what keeps them away, so I treat this list of 226 interacting supplements and herbs with real care, especially the nine rated major. More than half of the entries can change how the liver clears the drug; grapefruit can raise its level while St.”

Reviewed by 2 · Jul 18, 2026

Open the Ethosuximide interaction page

One more smart check

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

We hold 113 real supplement products containing Costus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Costus. Even though Costus itself has no known interaction with Ethosuximide, 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 Costus and Ethosuximide 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 Costus
Top half

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

29 days ago today
Medication Ethosuximide
Steady interest

#1,951 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 Costus reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Costus and Ethosuximide records this page draws on were last updated July 10, 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 Costus

What is Costus?

  • Digestive upset and gas
  • Cough and breathing complaints
  • Skin conditions (topical)
  • Worm and parasite remedies (traditional)
  • General tonic in traditional medicine

Costus (Saussurea costus) is a root used in Ayurvedic, Unani, and traditional Chinese medicine, mostly for digestive and respiratory complaints. High-quality human evidence is very limited, so its benefits are not well proven. Talk with a pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Saussurea costus · Asteraceae · Dried roots and root essential oil · Dried root powder, capsules, decoctions (teas), essential oil, and topical pastes

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

Costus: dosing

There is no well-established or standardized dose of costus for any health condition. Traditional preparations vary widely, and the strength of commercial products is not consistent.If you choose to use a costus product, follow the directions on the label and do not exceed them. The essential oil is very concentrated and should not be taken by mouth without professional guidance.

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

Read the full Costus monograph & all interactions
Medication

About Ethosuximide

What Is Ethosuximide Used For?

Brand name: Zarontin

Ethosuximide — sold as Zarontin and also available as generic Ethosuximide — is used to control absence (petit mal) epilepsy. Absence seizures are brief episodes where a person loses awareness for a few seconds, often mistaken for daydreaming.

Both Zarontin and Ethosuximide products (capsule and oral solution forms) are approved for this use. Either may also be used alongside other seizure medicines when a patient has absence seizures together with other types of epilepsy.

Most-Reported Side Effects for Ethosuximide

From FAERS, the FDA’s public side-effect reporting system (2,490 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Seizure 367 reports
Somnolence 157 reports
Generalised tonic-clonic seizure 149 reports
Petit mal epilepsy 118 reports
Treatment failure 116 reports
See full Ethosuximide drug information
Keep checking

Other Drugs & Costus

Browse every other medication we’ve checked against Costus — 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
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Costus list.

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

Costus References

The 6 references that drive our Costus 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. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  2. Marzulli, F. N. and Maibach, H. I. Effects of vehicles and elicitation concentration in contact dermatitis testing. I. Experimental contact sensitization in humans. Contact Dermatitis 1976;2(6):325-329. PubMed
  3. Mitchell, J. C. Contact hypersensitivity to some perfume materials. Contact Dermatitis 1975;1(4):196-199. PubMed
  4. Benezra, C. and Epstein, W. L. Molecular recognition patterns of sesquiterpene lactones in costus-sensitive patients. Contact Dermatitis 1986;15(4):223-230. PubMed
  5. Mitchell, J. C. and Epstein, W. L. Contact hypersensitivity to a perfume material, Costus Absolute. The role of sesquiterpene lactones. Arch.Dermatol 1974;110(6):871-873. DOI
  6. Cheminat, A., Stampf, J. L., Benezra, C., Farrall, M. J., and Frechet, J. M. Allergic contact dermatitis to costus: removal of haptens with polymers. Acta Derm.Venereol. 1981;61(6):525-529. DOI

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 Costus and Ethosuximide Together: Common Questions

Is it safe to take Costus with Ethosuximide?
We do not list a known interaction between Costus and Ethosuximide. 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 Costus and Ethosuximide have any of the same side effects?
Yes — our sources link each of them separately to one 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.
Does Ethosuximide interact with any supplements?
Yes. Ethosuximide has documented interactions with 226 supplements in our database — Costus is not one of them. The Ethosuximide 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

Costus monograph Uses, safety profile, and every drug interaction in one place Ethosuximide drug information The full plain-English guide to this medication Ethosuximide supplement interactions Every supplement checked against Ethosuximide, 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 6 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Ethosuximide and Costus?

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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.