Drug & supplement interaction

Activated Charcoal + Timothy Grass Pollen Allergen Extract

Timothy Grass Pollen Allergen Extract brand name: Grastek.

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

Activated Charcoal has a major interaction with Timothy Grass Pollen Allergen Extract. Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the route of administration.

Read the full interaction report
SeverityMajor
LikelihoodProbable
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Activated Charcoal and Timothy Grass Pollen Allergen Extract

Here is the interaction we found between these two, with the evidence behind it.

Major

ORAL DRUGS

Why this applies to Timothy Grass Pollen Allergen Extract

Timothy Grass Pollen Allergen Extract falls under ORAL DRUGS — the group Activated Charcoal interacts with.

Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the route of administration.
Activated charcoal adsorbs various drugs and may reduce their absorption and/or half-life. Examples of affected drugs include acetaminophen, aminophylline, amiodarone, atenolol, carbamazepine, dapsone, digoxin, disopyramide, fluoxetine, indomethacin, moxifloxacin, nadolol, phenytoin, phenobarbital, piroxicam, quinine, sotalol, theophylline, tricyclic antidepressants, valproate, and verapamil. Avoid co-administration, except after drug overdose.
Severity Major Likelihood Probable Evidence B

Interaction 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..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing about Grastek: it's a dissolvable tablet you place under your tongue, where it works on the tissue right there in your mouth. Activated charcoal does its binding down in your stomach and intestines, so the two don't really meet in the same place. Because of that, charcoal isn't likely to soak up your allergy tablet the way it would a pill you swallow and absorb through your gut.

That said, timing matters and so does common sense. If you happen to swallow any of the tablet, charcoal could grab onto it. I'd keep these spaced apart and run it by your pharmacist or allergist, just so you get the full benefit of your allergy treatment.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Anon. Position statement and practice guidelines on the use of multi-dose activated charcoal in the treatment of acute poisoning. American Academy of Clinical Toxicology; European Association of Poisons Centres and Clinical Toxicologists. J Toxicol Clin T
  2. Hoegberg LC, Angelo HR, Christophersen AB, Christensen HR. Effect of ethanol and pH on the adsorption of acetaminophen (paracetamol) to high surface activated charcoal, in vitro studies. J Toxicol Clin Toxicol 2002;40:59-67. PubMed
  3. Brahmi N, Kouraichi N, Thabet H, Amamou M. Influence of activated charcoal on the pharmacokinetics and the clinical features of carbamazepine poisoning. Am J Emerg Med 2006;24(4):440-3. PubMed
  4. Gude AB, Hoegberg LC, Angelo HR, Christensen HR. Dose-dependent adsorptive capacity of activated charcoal for gastrointestinal decontamination of a simulated paracetamol overdose in human volunteers. Basic Clin Pharmacol Toxicol 2010;106(5)406-10. PubMed
  5. Wananukul W, Klaikleun S, Sriapha C, Tongpoo A. Effect of activated charcoal in reducing paracetamol absorption at supra-therapeutic dose. J Med Assoc Thai 2010;93(10):1145-9.
  6. Wang X, Mondal S, Wang J, et al. Effect of activated charcoal on apixaban pharmacokinetics in healthy subjects. Am J Cardiovasc Drugs 2014;14(2):147-54. PubMed
  7. Chyka PA, Seger D, Krenzelok EP, et al. Position paper: single-dose activated charcoal. Clin Toxicol (Phila) 2005;43(2):61-87. PubMed
  8. Chiew AL, Gluud C, Brok J, Buckley NA. Interventions for paracetamol (acetaminophen) overdose. Cochrane Database Syst Rev 2018;2:CD003328. PubMed
  9. Skov K, Graudal NA, Jürgens G. The effect of activated charcoal on drug exposure following intravenous administration: A meta-analysis. Basic Clin Pharmacol Toxicol 2021;128(4):568-578. 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

Activated Charcoal Also Interacts With Other Medications

Activated Charcoal has 2,021 major, 5 moderate known drug interactions in our database — the Timothy Grass Pollen Allergen Extract one above is one of them. If you take anything else, check it against the full list below.

Major 2,021 Moderate 5 No known interaction 804 (incl. Timothy Grass Pollen Allergen Extract)
Taking anything else?

Check Another of Your Medications Against Activated Charcoal

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

From our Q&A

Questions About Activated Charcoal or Timothy Grass Pollen Allergen Extract

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Activated Charcoal or Timothy Grass Pollen Allergen Extract, 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 Timothy Grass Pollen Allergen Extract

This page covers Activated Charcoal only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Timothy Grass Pollen Allergen Extract page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate), Guar Gum (moderate) and Gum Arabic (moderate).

By severity: 1 major · 7 moderate · 9 minor.

From our pharmacist’s overview on the Timothy Grass Pollen Allergen Extract page

“A daily under-the-tongue allergy tablet might seem like an odd match for supplement trouble, but timothy grass pollen allergen extract (Grastek) has 17 herbal and supplement ingredients flagged against it, and this is a list that earns real caution, mainly for one entry. Activated charcoal, the sole major-rated interaction, binds many…”

Reviewed by 2 · Jul 18, 2026

Open the Timothy Grass Pollen Allergen Extract interaction page

One more smart check

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

We hold 256 real supplement products containing Activated Charcoal, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Activated Charcoal. Your product may carry other ingredients that interact with Timothy Grass Pollen Allergen Extract too, on top of Activated Charcoal — 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 Activated Charcoal and Timothy Grass Pollen Allergen Extract 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 Activated Charcoal
Top 25%

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

29 days ago today
Medication Timothy Grass Pollen Allergen Extract
Top half

#1,025 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 Activated Charcoal

What is Activated Charcoal?

Activated Charcoal
  • Poisoning and drug overdose (in emergency care)
  • Gas and bloating
  • Upset stomach
  • Diarrhea
  • Teeth whitening
  • General 'detox'

Activated charcoal is a highly porous form of carbon that can bind certain substances in the gut, and it is used in hospitals to treat some poisonings and overdoses. For everyday uses like gas, bloating, detox, or teeth whitening, the evidence is weak or unclear. If you suspect a poisoning, call your local poison control center or seek emergency care first rather than using a home product.

Read the full Activated Charcoal monograph & all interactions
Keep checking

Other Drugs & Activated Charcoal

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

2,021Major
5Moderate
0Minor
803No known interaction
2,021 Major 5 Moderate 803 No interaction
Major

2,021 interactions

Showing 60 of 2,021 major interactions — see all 2,021 on the Activated Charcoal page.

Moderate

5 interactions

No interaction 803 drugs checked — show the list

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

Showing the 60 most looked-up of 803 medications checked with no known interaction — see the full Activated Charcoal list.

See the full Activated Charcoal interactions page
See every supplement checked against Timothy Grass Pollen Allergen Extract, 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
Activated Charcoal monograph › Uses, safety, and every drug interaction in one place Timothy Grass Pollen Allergen Extract supplement interactions › Every supplement checked against Timothy Grass Pollen Allergen Extract, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Activated Charcoal and Timothy Grass Pollen Allergen Extract Together: Common Questions

Can you take Activated Charcoal with Timothy Grass Pollen Allergen Extract?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Activated Charcoal and Timothy Grass Pollen Allergen Extract interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Timothy Grass Pollen Allergen Extract and Activated Charcoal?

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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.