Drug & supplement interaction

Neem + Montelukast Sodium

Montelukast Sodium brand name: Singulair.

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

Neem has a moderate interaction with Montelukast Sodium. Theoretically, neem leaf extract might increase the levels and clinical effects of CYP2C9 substrates.

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

Neem and Montelukast Sodium

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

Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

Why this applies to Montelukast Sodium

Montelukast Sodium falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES — the group Neem interacts with.

Theoretically, neem leaf extract might increase the levels and clinical effects of CYP2C9 substrates.
In vitro research shows that neem leaf methanol extract inhibits CYP2C9 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 for your Singulair (montelukast). Your liver uses an enzyme called CYP2C9 to help break this medicine down. In test-tube studies, neem leaf extract seems to slow that same enzyme. If that happened in your body, montelukast could clear more slowly and build up a little, which in theory might bump up its usual side effects like headache, stomach upset, tiredness, or unusual mood changes.

I want to be honest about the strength of this, though. So far this has only been seen in lab dishes, never reported in real people, so it's more of a theoretical caution than a proven problem. Montelukast isn't a prodrug, so the direction (more effect, not less) holds. Before pairing them, just check with your pharmacist or doctor.

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 1,012 moderate known drug interactions in our database — the Montelukast Sodium one above is one of them. If you take anything else, check it against the full list below.

Moderate 1,012 No known interaction 1,818 (incl. Montelukast Sodium)
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.

From our Q&A

Questions About Neem or Montelukast Sodium

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Neem or Montelukast Sodium, 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 Montelukast Sodium

This page covers Neem only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Montelukast Sodium page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Adrafinil (moderate), African Wild Potato (moderate), Bacopa (moderate) and Berberine (moderate).

By severity: 1 major · 56 moderate · 24 minor.

From our pharmacist’s overview on the Montelukast Sodium page

“If you rely on montelukast (Singulair) for asthma or allergies, this list deserves genuine attention. The one major-rated concern is activated charcoal, which can soak up the medicine in your gut before it absorbs, leaving you with a weaker dose just when your airways need a steady one.”

Reviewed by 2 · Jul 18, 2026

Open the Montelukast Sodium 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 Montelukast Sodium 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 Montelukast Sodium 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%

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

29 days ago today
Medication Montelukast Sodium
Top 5%

#128 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
Medication

About Montelukast

What Is Montelukast Used For?

Brand name: Singulair

Montelukast is used for the long-term prevention and treatment of asthma in children and adults, and for preventing breathing problems triggered by exercise (exercise-induced bronchoconstriction). It is also used to relieve symptoms of seasonal allergic rhinitis (hay fever) and perennial allergic rhinitis (year-round nasal allergies). The age ranges covered depend on the specific product form — tablets, chewable tablets, and oral granules are each approved for different age groups.

For allergic rhinitis, montelukast should be reserved for people who haven't responded well to other treatments, because its potential mental health risks may outweigh the benefits when nasal allergy symptoms are mild and other options work. It is not a rescue treatment for sudden asthma attacks — always keep a fast-acting inhaler on hand.

See full Montelukast drug information
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
1,012Moderate
0Minor
1,817No known interaction
1,012 Moderate 1,817 No interaction
Moderate

1,012 interactions

Showing 60 of 1,012 moderate interactions — see all 1,012 on the Neem page.

No interaction 1,817 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 1,817 medications checked with no known interaction — see the full Neem list.

See the full Neem interactions page
See every supplement checked against Montelukast Sodium, 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 Montelukast Sodium supplement interactions › Every supplement checked against Montelukast Sodium, ranked by severity Montelukast drug information › The full plain-English guide to this medication 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 Montelukast Sodium Together: Common Questions

Can you take Neem with Montelukast Sodium?
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.
How serious is the Neem and Montelukast Sodium 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 Montelukast Sodium 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.