Drug & supplement interaction

Anhydrous Crystalline Maltose + Promethazine

Promethazine brand name: Phenergan.

No Known Interaction
Medically reviewed by · Updated June 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Anhydrous Crystalline Maltose 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.

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Interaction report

Anhydrous Crystalline Maltose 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 Anhydrous Crystalline Maltose 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.

Anhydrous Crystalline Maltose safety at a glance

Anhydrous Crystall... overall Use caution Generally well tolerated in studies, but it is a sugar, so people with diabetes should be cautious.
Pregnancy Use caution Not well studied as a supplement in pregnancy; check with your doctor before use.
Breastfeeding Use caution Not well studied during breastfeeding; check with your doctor before use.

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

Still wondering about combining Promethazine and Anhydrous Crystalline Maltose? 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. Anhydrous Crystalline Maltose has documented interactions with 1 drug class — the most serious being antidiabetes drugs (minor) — 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

Anhydrous Crystalline Maltose Does Interact With Other Medications

Anhydrous Crystalline Maltose has 86 minor known drug interactions in our database — Promethazine isn’t one of them. If you take anything else, check it against the full list below.

Minor 86 No known interaction 2,744 (incl. Promethazine)
Taking anything else?

Check Another of Your Medications Against Anhydrous Crystalline Maltose

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

What to actually watch for

What Promethazine’s Own FDA Label Lists

This is not an interaction — none of it involves Anhydrous Crystalline Maltose. These are the most notable effects listed in the ADVERSE REACTIONS section of Promethazine’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 10 of them are worth acting on rather than waiting out — marked below.

  • A slow heartbeat Worth acting on
  • Hallucinations Worth acting on
  • Yellowing of the skin or eyes Worth acting on
  • Wheezing Worth acting on
  • Confusion Worth acting on
  • Seizures Worth acting on
  • A low platelet count Worth acting on
  • Hives Worth acting on
  • A low white blood cell count Worth acting on
  • Bleeding or bruising Worth acting on

Showing the 10 most notable of 26 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Promethazine. Read the label on DailyMed › 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. Anhydrous Crystalline Maltose’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Anhydrous Crystalline Maltose side to compare — that is a limit of the record, not a statement that Anhydrous Crystalline Maltose has no side effects.

From our Q&A

Questions About Anhydrous Crystalline Maltose 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 Anhydrous Crystalline Maltose 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 Anhydrous Crystalline Maltose 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

How much people look this up

Where Anhydrous Crystalline Maltose 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 Anhydrous Crystalline Maltose
Steady interest

#1,073 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Promethazine
Top half

#1,050 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 Anhydrous Crystalline Maltose reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Anhydrous Crystalline Maltose and Promethazine records this page draws on were last updated June 22, 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 Anhydrous Crystalline Maltose

What is Anhydrous Crystalline Maltose?

Anhydrous Crystalline Maltose
  • Dry mouth (xerostomia)
  • Sjögren syndrome
  • Dry mouth from medications
  • Food stabilizer and texturizer

Anhydrous crystalline maltose is a starch-derived sugar (also called malt sugar) studied mainly as a slow-dissolving lozenge to ease dry mouth, including in people with Sjögren syndrome. Some studies suggest it may modestly improve saliva flow, but the overall evidence is limited. It appears generally well tolerated, but talk with your pharmacist or doctor before using it, especially if you have diabetes.

Disaccharide sugar derived from starch · Dissolving lozenges, tablets, powder

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

Anhydrous Crystalline Maltose: dosing

There is no official, standardized supplement dose for anhydrous crystalline maltose. Do not assume more is better.

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

Read the full Anhydrous Crystalline Maltose 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 & Anhydrous Crystalline Maltose

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

0Major
0Moderate
86Minor
2,743No known interaction
86 Minor 2,743 No interaction
Minor

86 interactions

Showing 60 of 86 minor interactions — see all 86 on the Anhydrous Crystalline Maltose page.

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Anhydrous Crystalline Maltose list.

See the full Anhydrous Crystalline Maltose interactions page
See every supplement checked against Promethazine, ranked by severity
Evidence & sources

Anhydrous Crystalline Maltose References

The 2 references that drive our Anhydrous Crystalline Maltose 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. Fox, P. C., Cummins, M. J., and Cummins, J. M. Use of orally administered anhydrous crystalline maltose for relief of dry mouth. J Altern Complement Med 2001;7(1):33-43. PubMed
  2. Fox, P. C., Cummins, M. J., and Cummins, J. M. A third study on the use of orally administered anhydrous crystalline maltose for relief of dry mouth in primary Sjogren's syndrome. J Altern Complement Med 2002;8(5):651-659.

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 Anhydrous Crystalline Maltose and Promethazine Together: Common Questions

Is it safe to take Anhydrous Crystalline Maltose with Promethazine?
We do not list a known interaction between Anhydrous Crystalline Maltose 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.
How was the Anhydrous Crystalline Maltose and Promethazine combination checked?
Interactions in our licensed database are recorded against drug classes. Promethazine is filed under 4 classifications, and Anhydrous Crystalline Maltose has documented interactions with 1 drug class — 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 Anhydrous Crystalline Maltose interact with any other medications?
Yes. Anhydrous Crystalline Maltose has 86 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 — Anhydrous Crystalline Maltose 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

Anhydrous Crystalline Maltose 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 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Promethazine and Anhydrous Crystalline Maltose?

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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.