Drug & supplement interaction

Timothy Grass + Fosaprepitant

Fosaprepitant brand names: Emend Injection, Focinvez.

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 Timothy Grass and Fosaprepitant 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

Timothy Grass and Fosaprepitant

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 Fosaprepitant and Timothy Grass 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 Timothy Grass at all — not against Fosaprepitant, 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.

Timothy Grass safety at a glance

Timothy Grass overall Use caution Standardized immunotherapy products are prescription-only and can cause allergic reactions, so they require medical supervision.
Pregnancy Use caution Starting allergy immunotherapy during pregnancy is generally not recommended; discuss with your doctor.
Breastfeeding Not established There is little safety data, so talk with your doctor before use while breastfeeding.

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

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

No Interaction Found — But Data Suggests Timothy Grass and Fosaprepitant May Share Several of the Same Side Effects

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. 2 of them are worth acting on rather than waiting out — marked below.

  • A severe allergic reaction Worth acting on Additional detail

    Timothy Grass

    “Timothy grass pollen is a common airborne allergen, causing allergic rhinitis in sensitive individuals. It is highly cross reactive with a variety of other grasses.

    Sublingually, timothy grass pollen allergen extract can cause local reactions at the site of application, including pruritus, oral blisters, nasopharyngitis, rhinitis, and throat irritation, which occur more frequently at the onset of treatment and with h…”

    Timothy Grass · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    6 sources cited
    1. 97287. Maloney J, Bernstein DI, Nelson H, et al. Efficacy and safety of grass sublingual immunotherapy tablet, MK-7243: a large, randomized controlled trial. Ann Allergy Asthma Immunol. 2014 Feb;112(2):146-153.e2. PubMed
    2. 15480. Dahl R, Stender A, Rak S. Specific immunotherapy with SQ standardized grass allergen tablets in asthmatics with rhinoconjunctivitis. Allergy 2006;61:185-90. PubMed
    3. 15483. Malling HJ, Lund L, Ipsen H, Poulsen L. Safety and immunological changes during sublingual immunotherapy with standardized quality grass allergen tablets. J Investig Allergol Clin Immunol 2006;16:162-8.
    4. 15485. Calderon M, Essendrop M. Specific immunotherapy with high dose SO standardized grass allergen tablets was safe and well tolerated. J Investig Allergol Clin Immunol 2006;16:338-44.
    5. 15486. Rak S, Yang WH, Pedersen MR, Durham SR. Once-daily sublingual allergen-specific immunotherapy improves quality of life in patients with grass pollen-induced allergic rhinoconjunctivitis: a double-blind, randomised study. Qual Life Res 2007;16:191-201. PubMed
    6. 15481. Casanovas M, Sastre J, Fernández-Nieto M, et al. Double-blind study of tolerability and antibody production of unmodified and chemically modified allergen vaccines of Phleum pratense. Clin Exp Allergy 2005;35:1377-83.

    “Timothy grass pollen is a common airborne allergen, causing allergic rhinitis upon exposure by sensitive individuals. Timothy grass is cross-reactive with a variety of other grasses, including cocksfoot, Kentucky bluegrass, perennial rye, sweet vernal, redtop, and meadow fescue. It is also partially cross-reactive with Johnson grass.”

    Timothy Grass · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    3 sources cited
    1. 97287. Maloney J, Bernstein DI, Nelson H, et al. Efficacy and safety of grass sublingual immunotherapy tablet, MK-7243: a large, randomized controlled trial. Ann Allergy Asthma Immunol. 2014 Feb;112(2):146-153.e2. PubMed
    2. 97282. Sola J, da Silva Ferreira JA, Dionicio Elera J, et al. Timothy grass pollen therapeutic vaccine: optimal dose for subcutaneous immunotherapy. Immunotherapy. 2016;8(3):251-63. PubMed
    3. 97286. Sola J, Sánchez V, Landeta A, Madariaga B, Martínez A, Álvarez-Cuesta E. A Phase I clinical trial with subcutaneous immunotherapy vaccine of Timothy grass pollen extract according to EMA guidelines. Immunotherapy. 2015;7(4):343-52. PubMed

    Fosaprepitant

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

  • Hives Worth acting on Additional detail

    Timothy Grass

    Recorded for Timothy Grass in the same Natural Medicines adverse-effect record shown under A severe allergic reaction above.

    Fosaprepitant

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

  • Itching Additional detail

    Timothy Grass

    Recorded for Timothy Grass in the same Natural Medicines adverse-effect record shown under A severe allergic reaction above.

    Fosaprepitant

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

Reported for Timothy Grass but not commonly for Fosaprepitant: sore throat, a stuffy or runny nose, wheezing and cough.

Effects for Fosaprepitant come from the ADVERSE REACTIONS section of its FDA label; effects for Timothy Grass come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 13,671 voluntary FDA FAERS reports for Fosaprepitant 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 Fosaprepitant

This page covers Timothy Grass only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosaprepitant page lists 141 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate), Adrafinil (moderate) and African Wild Potato (moderate).

By severity: 2 major · 109 moderate · 30 minor.

From our pharmacist’s overview on the Fosaprepitant page

“Fosaprepitant (Emend Injection, Focinvez) is the IV drug that keeps chemotherapy from making you sick, so anything that undercuts it costs you real comfort, and I would treat this list with genuine care before adding a supplement to it. Nearly all 141 entries hinge on one liver enzyme, CYP3A4, and the traffic runs both ways, since some…”

Reviewed by 2 · Jul 18, 2026

Open the Fosaprepitant interaction page

How much people look this up

Where Timothy Grass and Fosaprepitant 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 Timothy Grass
Steady interest

#1,047 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Fosaprepitant
Top half

#1,080 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 Timothy Grass reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Timothy Grass and Fosaprepitant 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 Timothy Grass

What is Timothy Grass?

  • Grass pollen allergy (hay fever)
  • Allergic rhinitis
  • Allergic conjunctivitis (itchy, watery eyes)
  • Allergy desensitization (immunotherapy)
  • Allergy testing

Timothy grass is a common grass whose pollen is a major cause of seasonal hay fever. In medicine, a purified, standardized form of its pollen is used in prescription allergy immunotherapy tablets and shots to gradually reduce allergic reactions. It is not a typical dietary supplement, and any product containing timothy grass allergen should be used only under medical supervision.

Phleum pratense · Poaceae · Pollen (used to make allergy extracts and immunotherapy products) · Sublingual immunotherapy tablets, allergen extracts for allergy testing and allergy shots

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

Timothy Grass: dosing

There is no general supplement dose for timothy grass. The amount of allergen in immunotherapy products is carefully standardized by the manufacturer, and the right product and schedule depend on the individual.Sublingual tablets are usually taken once daily, often started before grass pollen season and continued as directed. Allergy shots follow a build-up and then maintenance schedule set by an allergist.Because dosing is specific and reactions are possible, you should only use timothy grass allergen products exactly as prescribed.

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

Read the full Timothy Grass monograph & all interactions
Medication

About Fosaprepitant

Most-Reported Side Effects for Fosaprepitant

From FAERS, the FDA’s public side-effect reporting system (13,671 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Nausea 1,478 reports
Dyspnea 1,268 reports
Fever 1,129 reports
Diarrhea 1,111 reports
Vomiting 1,081 reports
Keep checking

Other Drugs & Timothy Grass

Browse every other medication we’ve checked against Timothy Grass — 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 Timothy Grass 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 Timothy Grass list.

See the full Timothy Grass interactions page
See every supplement checked against Fosaprepitant, ranked by severity
Evidence & sources

Timothy Grass References

The 10 references that drive our Timothy Grass 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. Dahl R, Stender A, Rak S. Specific immunotherapy with SQ standardized grass allergen tablets in asthmatics with rhinoconjunctivitis. Allergy 2006;61:185-90. PubMed
  2. Casanovas M, Sastre J, Fernández-Nieto M, et al. Double-blind study of tolerability and antibody production of unmodified and chemically modified allergen vaccines of Phleum pratense. Clin Exp Allergy 2005;35:1377-83.
  3. Roberts G, Hurley C, Turcanu V, Lack G. Grass pollen immunotherapy as an effective therapy for childhood seasonal allergic asthma. J Allergy Clin Immunol 2006;117:263-8. PubMed
  4. Malling HJ, Lund L, Ipsen H, Poulsen L. Safety and immunological changes during sublingual immunotherapy with standardized quality grass allergen tablets. J Investig Allergol Clin Immunol 2006;16:162-8.
  5. Calderon M, Essendrop M. Specific immunotherapy with high dose SO standardized grass allergen tablets was safe and well tolerated. J Investig Allergol Clin Immunol 2006;16:338-44.
  6. Rak S, Yang WH, Pedersen MR, Durham SR. Once-daily sublingual allergen-specific immunotherapy improves quality of life in patients with grass pollen-induced allergic rhinoconjunctivitis: a double-blind, randomised study. Qual Life Res 2007;16:191-201. PubMed
  7. Rossi RE, Monasterolo G, Coco G, et al. Evaluation of serum IgG4 antibodies specific to grass pollen allergen components in the follow up of allergic patients undergoing subcutaneous and sublingual immunotherapy. Vaccine 2007;25:957-64. PubMed
  8. Sola J, da Silva Ferreira JA, Dionicio Elera J, et al. Timothy grass pollen therapeutic vaccine: optimal dose for subcutaneous immunotherapy. Immunotherapy. 2016;8(3):251-63. PubMed
  9. Sola J, Sánchez V, Landeta A, Madariaga B, Martínez A, Álvarez-Cuesta E. A Phase I clinical trial with subcutaneous immunotherapy vaccine of Timothy grass pollen extract according to EMA guidelines. Immunotherapy. 2015;7(4):343-52. PubMed
  10. Maloney J, Bernstein DI, Nelson H, et al. Efficacy and safety of grass sublingual immunotherapy tablet, MK-7243: a large, randomized controlled trial. Ann Allergy Asthma Immunol. 2014 Feb;112(2):146-153.e2. PubMed

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 Timothy Grass and Fosaprepitant Together: Common Questions

Is it safe to take Timothy Grass with Fosaprepitant?
We do not list a known interaction between Timothy Grass and Fosaprepitant. 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 Timothy Grass and Fosaprepitant have any of the same side effects?
Yes — our sources link each of them separately to 3 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 Fosaprepitant interact with any supplements?
Yes. Fosaprepitant has documented interactions with 141 supplements in our database — Timothy Grass is not one of them. The Fosaprepitant 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

Timothy Grass monograph Uses, safety profile, and every drug interaction in one place Fosaprepitant supplement interactions Every supplement checked against Fosaprepitant, 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 10 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Fosaprepitant and Timothy Grass?

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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.