Drug & supplement interaction

Lemongrass + Acetaminophen, Chlorpheniramine, Phenylephrine

Acetaminophen, Chlorpheniramine, Phenylephrine brand names: Protid, Histex SR, Alka-Seltzer PLUS.

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

Acetaminophen, Chlorpheniramine, Phenylephrine falls into 2 drug categories that Lemongrass can interact with; the most serious is rated moderate. Theoretically, lemongrass might decrease the metabolism of CYP3A4 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Lemongrass and Acetaminophen, Chlorpheniramine, Phenylephrine

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

Why Are There 2 Interactions?

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

1 of 2

Why this applies to Acetaminophen, Chlorpheniramine, Phenylephrine

Acetaminophen, Chlorpheniramine, Phenylephrine falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Lemongrass interacts with.

Theoretically, lemongrass might decrease the metabolism of CYP3A4 substrates.
Animal research shows that lemongrass and its constituent citral inhibit CYP3A4.
Severity Moderate 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

This cold-and-allergy combo pairs acetaminophen (a pain and fever reducer) with chlorpheniramine (an antihistamine) and phenylephrine (a decongestant). The thinking here is that lemongrass — mainly its compound citral — may slow down a liver enzyme called CYP3A4 that helps clear some of these ingredients. If that enzyme works slower, a bit more of the drug could linger, which in theory might nudge up side effects like drowsiness, dry mouth, dizziness, or a faster heartbeat.

Here's the honest part: this concern comes only from lab and animal studies, not real human cases, so it's more of a theoretical caution than a proven problem. A cup of lemongrass tea or its use as a cooking herb is very unlikely to matter. Concentrated extracts or the essential oil are where I'd be more careful — check with your pharmacist before combining those.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Li CC, Yu HF, Chang CH, Liu YT, Yao HT. Effects of lemongrass oil and citral on hepatic drug-metabolizing enzymes, oxidative stress, and acetaminophen toxicity in rats. J Food Drug Anal 2018;26(1):432-8. PubMed
Moderate

GLUCURONIDATED DRUGS

2 of 2

Acetaminophen, Chlorpheniramine, Phenylephrine also falls under GLUCURONIDATED DRUGS.

Theoretically, lemongrass might increase the clearance and decrease the levels of glucuronidated drugs.
Animal research shows that lemongrass and its constituent citral induce uridine diphosphoglucuronosyl transferase (UGT), the major phase 2 enzyme that is responsible for glucuronidation.
Severity Moderate 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

This is one of those interactions that looks bigger on paper than it usually is in real life. Your cold and allergy combo contains acetaminophen (Tylenol), which your body partly clears through a process called glucuronidation. In animal and test-tube studies, lemongrass and its citral compounds seem to speed up that clearing enzyme. In theory, that could lower acetaminophen levels a bit and make it slightly less effective for pain or fever.

Honestly, the evidence here is weak and comes only from lab work, not people. The lemongrass in your tea or cooking is very unlikely to matter. Concentrated supplements or the essential oil are a different story, so if you use those regularly, just run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Li CC, Yu HF, Chang CH, Liu YT, Yao HT. Effects of lemongrass oil and citral on hepatic drug-metabolizing enzymes, oxidative stress, and acetaminophen toxicity in rats. J Food Drug Anal 2018;26(1):432-8. 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

Lemongrass Also Interacts With Other Medications

Lemongrass has 707 moderate known drug interactions in our database — the Acetaminophen, Chlorpheniramine, Phenylephrine one above is among them. If you take anything else, check it against the full list below.

Moderate 707 No known interaction 2,123 (incl. Acetaminophen, Chlorpheniramine, Phenylephrine)
Taking anything else?

Check Another of Your Medications Against Lemongrass

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

Everything else you take

See Every Supplement That Interacts With Acetaminophen, Chlorpheniramine, Phenylephrine

This page covers Lemongrass only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Chlorpheniramine, Phenylephrine page lists 292 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Ephedra (major) and Grapefruit (major).

By severity: 14 major · 232 moderate · 46 minor.

From our pharmacist’s overview on the Acetaminophen, Chlorpheniramine, Phenylephrine page

“Picture the week you are sick enough to reach for Alka-Seltzer PLUS or another acetaminophen, chlorpheniramine, and phenylephrine combination, while still taking whatever supplements you always take. That is where trouble hides, and with 14 of its 292 supplement interactions rated major, this medicine warrants real vigilance.”

Reviewed by 2 · Jul 18, 2026

Open the Acetaminophen, Chlorpheniramine, Phenylephrine interaction page

One more smart check

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

We hold 417 real supplement products containing Lemongrass, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lemongrass. Your product may carry other ingredients that interact with Acetaminophen, Chlorpheniramine, Phenylephrine too, on top of Lemongrass — 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 Lemongrass and Acetaminophen, Chlorpheniramine, Phenylephrine 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 Lemongrass
Top 25%

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

29 days ago today
Medication Acetaminophen, Chlorpheniramine, Phenylephrine
Top 25%

#518 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 Lemongrass

What is Lemongrass?

Lemongrass
  • Digestive upset
  • Anxiety and stress
  • Antimicrobial/antifungal
  • Insect repellent
  • Flavoring in food and drinks

Lemongrass is a fragrant tropical grass widely used as a cooking herb, a tea, and an aromatherapy oil. It is generally considered safe in the small amounts used in food, but most of its claimed health benefits come from laboratory or animal studies rather than strong human research. Talk with your pharmacist or doctor before using concentrated supplements or the essential oil, especially if you are pregnant or breastfeeding.

Read the full Lemongrass monograph & all interactions
Keep checking

Other Drugs & Lemongrass

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

0Major
707Moderate
0Minor
2,122No known interaction
707 Moderate 2,122 No interaction
Moderate

707 interactions

Showing 60 of 707 moderate interactions — see all 707 on the Lemongrass page.

No interaction 2,122 drugs checked — show the list

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

Showing the 60 most looked-up of 2,122 medications checked with no known interaction — see the full Lemongrass list.

See the full Lemongrass interactions page
See every supplement checked against Acetaminophen, Chlorpheniramine, Phenylephrine, 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
Lemongrass monograph › Uses, safety, and every drug interaction in one place Acetaminophen, Chlorpheniramine, Phenylephrine supplement interactions › Every supplement checked against Acetaminophen, Chlorpheniramine, Phenylephrine, 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 Lemongrass and Acetaminophen, Chlorpheniramine, Phenylephrine Together: Common Questions

Can you take Lemongrass with Acetaminophen, Chlorpheniramine, Phenylephrine?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Lemongrass and Acetaminophen, Chlorpheniramine, Phenylephrine?
Acetaminophen, Chlorpheniramine, Phenylephrine belongs to more than one drug category, and Lemongrass 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 Lemongrass and Acetaminophen, Chlorpheniramine, Phenylephrine interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Acetaminophen, Chlorpheniramine, Phenylephrine and Lemongrass?

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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.