Drug & supplement interaction

Neem + Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr

Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr brand name: Vicks Formula 44M Cough, Cold & Flu Relief.

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

Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr falls into 2 drug categories that Neem can interact with; the most serious is rated moderate. Theoretically, neem leaf extract might increase the levels and clinical effects of CYP1A2 substrates.

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

Neem and Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr

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

Why Are There 2 Interactions?

Neem interacts with whole categories of medication. Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr falls into 2 of those categories, so it can interact with Neem 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 1A2 (CYP1A2) SUBSTRATES

1 of 2

Why this applies to Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr

Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Neem interacts with.

Theoretically, neem leaf extract might increase the levels and clinical effects of CYP1A2 substrates.
In vitro research shows that neem leaf extract inhibits CYP1A2 enzymes. So far, this reaction has not been reported in humans.
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

Here's the gist with this combination cough and cold product (the acetaminophen, chlorpheniramine, and dextromethorphan blend). In lab dishes, neem leaf extract appears to slow down a liver enzyme called CYP1A2. That enzyme helps process certain medicines, so in theory neem could let some of these ingredients linger a bit longer and feel a touch stronger. If that happened, you might notice more drowsiness or dry mouth from the chlorpheniramine, or feeling more woozy from the dextromethorphan.

I want to be honest though: this is only test-tube data, and it has never been reported in real people. So I'm not losing sleep over it. Still, since neem itself can be harsh if swallowed, it's worth a quick chat with your pharmacist before pairing them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Amaeze O, Marques ES, Wei W, et al. Evaluation of Nigerian Medicinal Plants Extract on Human P-glycoprotein and Cytochrome P450 Enzyme Induction: Implications for Herb-drug Interaction. Curr Drug Metab. 2021;22(14):1103-1113. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 2

Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, neem leaf extract might increase the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that neem leaf methanol extract inhibits CYP3A4 enzymes. So far, this reaction has not been reported in humans.
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 combo cold medicine has three ingredients, and one of them, dextromethorphan (the cough suppressant), is partly broken down by an enzyme in your body called CYP3A4. In test-tube studies, neem leaf extract seems to slow that same enzyme down. In theory, that could let a little more dextromethorphan build up, which might mean more drowsiness, dizziness, or feeling foggy. The chlorpheniramine (an antihistamine) already causes sleepiness, so you could notice that more.

Here's the honest part: this is only lab data, and it has never been reported in real people. So I wouldn't lose sleep over it. Still, since both share a sedating side, it's worth a quick word with your pharmacist before pairing them, especially if you take neem in concentrated capsule form.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Amaeze O, Eng H, Horlbogen L, Varma MVS, Slitt A. Cytochrome P450 Enzyme Inhibition and Herb-Drug Interaction Potential of Medicinal Plant Extracts Used for Management of Diabetes in Nigeria. Eur J Drug Metab Pharmacokinet. 2021;46(3):437-450. 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

Neem Also Interacts With Other Medications

Neem has 1,013 moderate known drug interactions in our database — the Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr one above is among them. If you take anything else, check it against the full list below.

Moderate 1,013 No known interaction 1,817 (incl. Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr)
Taking anything else?

Check Another of Your Medications Against Neem

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

Everything else you take

See Every Supplement That Interacts With Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr

This page covers Neem only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr page lists 275 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), Grapefruit (major) and Henbane (major).

By severity: 10 major · 220 moderate · 45 minor.

From our pharmacist’s overview on the Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr page

“A three-drug cold formula like Vicks Formula 44M (acetaminophen, chlorpheniramine, and dextromethorphan) gives supplements three separate targets, so its interaction list warrants real vigilance, starting with the ten major-rated entries. The dominant patterns track each ingredient.”

Reviewed by 2 · Jul 18, 2026

Open the Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr interaction page

One more smart check

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

We hold 288 real supplement products containing Neem, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Neem. Your product may carry other ingredients that interact with Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr too, on top of Neem — 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 Neem and Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr 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 Neem
Top 25%

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

29 days ago today
Medication Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr
Top 10%

#181 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 Neem

What is Neem?

Neem
  • Skin conditions
  • Dental and gum health
  • Antimicrobial and antiparasitic
  • Digestive upset
  • Blood sugar support
  • Insect repellent/pesticide

Neem is a tree from India used for centuries in traditional medicine, especially for skin, dental, and antimicrobial purposes. Some small studies are promising for oral health and skin, but high-quality human evidence is limited for most uses. Neem oil and seed extracts can be toxic if swallowed, especially in children, so use with caution and talk to your pharmacist or doctor first.

Read the full Neem monograph & all interactions
Keep checking

Other Drugs & Neem

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

0Major
1,013Moderate
0Minor
1,816No known interaction
1,013 Moderate 1,816 No interaction
Moderate

1,013 interactions

Showing 60 of 1,013 moderate interactions — see all 1,013 on the Neem page.

No interaction 1,816 drugs checked — show the list

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

Showing the 60 most looked-up of 1,816 medications checked with no known interaction — see the full Neem list.

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

Can you take Neem with Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr?
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 Neem and Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr?
Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr belongs to more than one drug category, and Neem 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 Neem and Acetaminophen, Chlorpheniramine Maleate, Dextromethorphan HBr 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 Maleate, Dextromethorphan HBr and Neem?

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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.