Drug & supplement interaction

Neem + Promethazine

Promethazine brand name: Phenergan.

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 Neem and Promethazine 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

Neem and Promethazine

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 Promethazine and Neem 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.

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.

Neem safety at a glance

Neem overall Use caution Leaf preparations are likely safe short-term for most adults, but neem oil and seed extracts can be toxic if swallowed.
Pregnancy Likely Unsafe When neem oil or leaf is used orally. Neem oil and leaf have been used as abortifacients. Read the full pregnancy detail
Breastfeeding Avoid There is not enough reliable safety information, so it is best avoided while breastfeeding.

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Promethazine and Neem? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Promethazine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Promethazine is filed under 4 classifications — including phenothiazines, anticholinergic drugs, photosensitizing drugs. Neem has documented interactions with 7 drug classes — the most serious being antidiabetes drugs (moderate), cytochrome p450 1a2 (cyp1a2) substrates (moderate) and cytochrome p450 2c8 (cyp2c8) substrates (moderate) — and none of Promethazine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Neem Does Interact With Other Medications

Neem has 1,013 moderate known drug interactions in our database — Promethazine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 1,013 No known interaction 1,817 (incl. Promethazine)
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.

What to actually watch for

No Interaction Found — But Data Suggests Neem and Promethazine 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.

  • Yellowing of the skin or eyes Worth acting on Additional detail

    Neem

    “Orally, neem leaf has been reported to cause hemolysis in adults. In one case report, a 35-year-old male with diabetes and glucose-6-phosphate dehydrogenase (G6PD) deficiency developed hemolytic anemia and jaundice after drinking several liters of neem tea daily for 3 weeks. All symptoms resolved after discontinuation and supportive treatment.”

    Neem · Natural Medicines adverse-effect record, reported in anemia.

    6 sources cited
    1. 12835. Boeke SJ, Boersma MG, Alink GM, et al. Safety evaluation of neem (Azadirachta indica) derived pesticides. J Ethnopharmacol 2004;94:25-41. PubMed
    2. 94571. Page C, Hawes EM. Haemolytic anaemia after ingestion of Neem (Azadirachta indica) tea. BMJ Case Rep. 2013. pii: bcr2013200890.
    3. 3473. Sinniah D, Baskaran G. Margosa oil poisoning as a cause of Reye's syndrome. Lancet 1981;1:487-9. PubMed
    4. 3474. Sinniah D, Baskaran G, Looi LM, Leong KL. Reye-like syndrome due to margosa oil poisoning: report of a case with postmortem findings. Am J Gastroenterol 1982;77:158-61.
    5. 3476. Lai SM, Lim KW, Cheng HK. Margosa oil poisoning as a cause of toxic encephalopathy. Singapore Med J 1990;31:463-5.
    6. 64865. Sinniah, D., Sinniah, R., Baskaran, G., Pathmanathan, R., Yamashita, F., and Yoshino, M. Evaluation of the possible role of glucose, carnitine, coenzyme Q10 and steroids in the treatment of Reye's syndrome using the margosa oil animal model. Acta Paediat PubMed

    Promethazine

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

  • Seizures Worth acting on Additional detail

    Neem

    “Orally, single doses of neem oil ranging from a few drops to 60 mL have been associated with reports of encephalopathy in infants and small children. Symptoms include drowsiness, seizure, loss of consciousness, coma, cerebral edema, Reye-like syndrome, and death within hours of ingestion. There is also at least one case report of neurotoxicity in an adult after ingestion of a neem-based pesticide.”

    Neem · Natural Medicines adverse-effect record, reported in epilepsy.

    6 sources cited
    1. 3473. Sinniah D, Baskaran G. Margosa oil poisoning as a cause of Reye's syndrome. Lancet 1981;1:487-9. PubMed
    2. 3474. Sinniah D, Baskaran G, Looi LM, Leong KL. Reye-like syndrome due to margosa oil poisoning: report of a case with postmortem findings. Am J Gastroenterol 1982;77:158-61.
    3. 3476. Lai SM, Lim KW, Cheng HK. Margosa oil poisoning as a cause of toxic encephalopathy. Singapore Med J 1990;31:463-5.
    4. 64855. Senanayake, M. P., Rupasinghe, S., and Dissanayake, P. V. Margosa (Kohomba) oil induced toxic encephalopathy following home remedy for intestinal worms. Ceylon Med.J 2009;54(4):140. PubMed
    5. 94750. Braidy N, Berg J, Clement J, et al. Role of nicotinamide dinucleotide and related precursors as therapeutic targets for age-related degenerative diseases: rationale, biochemistry, pharmacokinetics, and outcomes. Antiox Redox Signal 2018.
    6. 64858. Iyyadurai, R., Surekha, V., Sathyendra, S., Paul, Wilson B., and Gopinath, K. G. Azadirachtin poisoning: a case report. Clin Toxicol.(Phila) 2010;48(8):857-858. PubMed

    Promethazine

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

  • Drowsiness / Swelling Additional detail

    Neem

    Recorded for Neem in the same Natural Medicines adverse-effect record shown under Seizures above.

    Promethazine

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

  • Vomiting reported in 8.0% of FDA reports for Promethazine Additional detail

    Neem

    “Orally, neem oil has been reported to cause vomiting and loose stools in infants and small children.”

    Neem · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    4 sources cited
    1. 3473. Sinniah D, Baskaran G. Margosa oil poisoning as a cause of Reye's syndrome. Lancet 1981;1:487-9. PubMed
    2. 3474. Sinniah D, Baskaran G, Looi LM, Leong KL. Reye-like syndrome due to margosa oil poisoning: report of a case with postmortem findings. Am J Gastroenterol 1982;77:158-61.
    3. 3476. Lai SM, Lim KW, Cheng HK. Margosa oil poisoning as a cause of toxic encephalopathy. Singapore Med J 1990;31:463-5.
    4. 64865. Sinniah, D., Sinniah, R., Baskaran, G., Pathmanathan, R., Yamashita, F., and Yoshino, M. Evaluation of the possible role of glucose, carnitine, coenzyme Q10 and steroids in the treatment of Reye's syndrome using the margosa oil animal model. Acta Paediat PubMed

    Promethazine

    Listed in the ADVERSE REACTIONS section of the FDA label for Promethazine, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • A skin rash Additional detail

    Neem

    “Topically, neem products have been associated with dermatologic reactions. Some case reports have associated the use of topical neem oil with contact dermatitis. In one case series, the topical application of neem seed extract shampoo was associated with skin irritation, red spots, and a burning feeling of the scalp.”

    Neem · Natural Medicines adverse-effect record, reported in dermatitis.

    5 sources cited
    1. 64851. Reutemann, P. and Ehrlich, A. Neem oil: an herbal therapy for alopecia causes dermatitis. Dermatitis 2008;19(3):E12-E15.
    2. 94568. Greenblatt DT, Banerjee P, White JM. Allergic contact dermatitis caused by neem oil. Contact Dermatitis. 2012;67(4):242-3. PubMed
    3. 102867. Giuggioli D, Lumetti F, Spinella A, et al. Use of Neem oil and Hypericum perforatum for treatment of calcinosis-related skin ulcers in systemic sclerosis. J Int Med Res 2019:300060519882176. Online ahead of print.
    4. 64848. Abdel-Ghaffar, F. and Semmler, M. Efficacy of neem seed extract shampoo on head lice of naturally infected humans in Egypt. Parasitol.Res 2007;100(2):329-332. PubMed
    5. 100958. Jadhav PB. Leucoderma on the lips induced by neem (Azadirachta indica): case series. Clin Exp Dermatol. 2018;43(8):943-6.

    Promethazine

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

Reported for Neem but not commonly for Promethazine: fainting, thoughts of self-harm, liver problems and kidney problems.

Effects for Promethazine come from the ADVERSE REACTIONS section of its FDA label; effects for Neem come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 22,361 voluntary FDA FAERS reports for Promethazine 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.

Special populations

Neem in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When neem oil or leaf is used orally. Neem oil and leaf have been used as abortifacients.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Neem or Promethazine

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 Promethazine, 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 Promethazine

This page covers Neem only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Promethazine page lists 83 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Henbane (major), Scopolia (major), Alfalfa (moderate) and Angel's Trumpet (moderate).

By severity: 3 major · 57 moderate · 23 minor.

From our pharmacist’s overview on the Promethazine page

“Promethazine (Phenergan) is a phenothiazine antihistamine used for allergies, nausea, and motion sickness, and it is strongly anticholinergic on its own, causing dry mouth, blurred vision, drowsiness, and constipation. That is why the 83 supplements and herbs on this list deserve real attention, starting with the three rated major.”

Reviewed by 2 · Jul 18, 2026

Open the Promethazine 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. Even though Neem itself has no known interaction with Promethazine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Neem and Promethazine 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%

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

29 days ago today
Medication Promethazine
Steady interest

#1,497 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 Neem reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Neem and Promethazine records this page draws on were last updated July 11, 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 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.

Azadirachta indica · Meliaceae · Leaves, seeds (and seed oil), bark, and twigs · Capsules, leaf powder, leaf extract, tea, topical oil, toothpaste, mouth rinse, and soap

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

Neem: dosing

There is no well-established standard dose for neem, and products vary widely in strength and form. Because of this, the safest approach is to follow the directions on the product label and not exceed the recommended amount.Topical products (like creams, soaps, and oils for the skin) and oral neem leaf supplements are used differently, so do not assume one form's instructions apply to another.

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

Read the full Neem monograph & all interactions
Medication

About Promethazine

What Is Promethazine Used For?

Brand name: Phenergan

Promethazine is used for a wide range of conditions. Tablets, oral solution, and rectal suppositories (brands including Phenergan, Promethegan, and Phenadoz) are approved for seasonal and perennial allergic rhinitis, vasomotor rhinitis, allergic conjunctivitis, hives (urticaria), angioedema, dermographism, and allergic reactions to blood or plasma. They are also used for motion sickness (both prevention and active treatment), nausea and vomiting related to anesthesia and surgery, sedation, and as a helper medication alongside pain relievers after surgery.

Promethazine hydrochloride injection (brands including Phenergan and Promethazine HCl injection) is used for many of the same purposes but is reserved for situations where oral treatment is not possible — including allergic emergencies as an adjunct to epinephrine, sedation during labor, and as an aid during certain surgical procedures such as bronchoscopy and eye surgery.

Most-Reported Side Effects for Promethazine

From FAERS, the FDA’s public side-effect reporting system (22,614 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dependence 3,586 reports
Nausea 2,646 reports
Vomiting 1,802 reports
Fatigue 1,496 reports
Diarrhea 1,341 reports
See full Promethazine 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
1,013Moderate
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 Promethazine, ranked by severity
Evidence & sources

Neem References

The 28 references that drive our Neem 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. Sinniah D, Baskaran G. Margosa oil poisoning as a cause of Reye's syndrome. Lancet 1981;1:487-9. PubMed
  2. Sinniah D, Baskaran G, Looi LM, Leong KL. Reye-like syndrome due to margosa oil poisoning: report of a case with postmortem findings. Am J Gastroenterol 1982;77:158-61.
  3. Sinniah R, Sinniah D, Chia LS, Baskaran G. Animal model of margosa oil ingestion with Reye-like syndrome. Pathogenesis of microvesicular fatty liver. J Pathol 1989;159:255-64. PubMed
  4. Lai SM, Lim KW, Cheng HK. Margosa oil poisoning as a cause of toxic encephalopathy. Singapore Med J 1990;31:463-5.
  5. Biswas K, Chattopadhyay I, Banerjee RK, Bandyopadhyay U. Biological activities and medicinal properties of neem (Azadirachta indica). Curr Sci 2002;82:1336-45.
  6. Upadhyay SN, Dhawan S, Garg S, Talwar GP. Immunomodulatory effects of neem (Azadirachta indica) oil. Int J Immunopharmacol 1992;14:1187-93. PubMed
  7. Ibrahim IA, Khalid SA, Omer SA, Adam SE. On the toxicology of Azadirachta indica leaves. J Ethnopharmacol 1992;35:267-73. PubMed
  8. Ali BH. Toxicology of Azadirachta indica. J Ethnopharmacol 1994;42:71-2. PubMed
  9. Boeke SJ, Boersma MG, Alink GM, et al. Safety evaluation of neem (Azadirachta indica) derived pesticides. J Ethnopharmacol 2004;94:25-41. PubMed
  10. Abdel-Ghaffar, F. and Semmler, M. Efficacy of neem seed extract shampoo on head lice of naturally infected humans in Egypt. Parasitol.Res 2007;100(2):329-332. PubMed
  11. Reutemann, P. and Ehrlich, A. Neem oil: an herbal therapy for alopecia causes dermatitis. Dermatitis 2008;19(3):E12-E15.
  12. Senanayake, M. P., Rupasinghe, S., and Dissanayake, P. V. Margosa (Kohomba) oil induced toxic encephalopathy following home remedy for intestinal worms. Ceylon Med.J 2009;54(4):140. PubMed
  13. Bhaskar, M. V., Pramod, S. J., Jeevika, M. U., Chandan, P. K., and Shetteppa, G. MR imaging findings of neem oil poisoning. AJNR Am J Neuroradiol. 2010;31(7):E60-E61.
  14. Iyyadurai, R., Surekha, V., Sathyendra, S., Paul, Wilson B., and Gopinath, K. G. Azadirachtin poisoning: a case report. Clin Toxicol.(Phila) 2010;48(8):857-858. PubMed
  15. Sinniah, D., Sinniah, R., Baskaran, G., Pathmanathan, R., Yamashita, F., and Yoshino, M. Evaluation of the possible role of glucose, carnitine, coenzyme Q10 and steroids in the treatment of Reye's syndrome using the margosa oil animal model. Acta Paediat 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 Neem and Promethazine Together: Common Questions

Is it safe to take Neem with Promethazine?
We do not list a known interaction between Neem and Promethazine. 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 Neem and Promethazine have any of the same side effects?
Yes — our sources link each of them separately to 6 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.
How was the Neem and Promethazine combination checked?
Interactions in our licensed database are recorded against drug classes. Promethazine is filed under 4 classifications, and Neem has documented interactions with 7 drug classes — none of Promethazine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Neem interact with any other medications?
Yes. Neem has 1,013 documented drug interactions in our database — Promethazine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Promethazine interact with any supplements?
Yes. Promethazine has documented interactions with 83 supplements in our database — Neem is not one of them. The Promethazine 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

Neem monograph Uses, safety profile, and every drug interaction in one place Promethazine drug information The full plain-English guide to this medication Promethazine supplement interactions Every supplement checked against Promethazine, 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 28 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Promethazine 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.