Drug & supplement interaction

Weight Watchers Diet + 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 Weight Watchers Diet 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

Weight Watchers Diet 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 Weight Watchers Diet in our sources. This does not guarantee that the combination is completely free of risk — research on Weight Watchers Diet alongside specific medications may be limited.

Weight Watchers Diet is an eating pattern rather than something you take. Ask your pharmacist or doctor before changing how you eat while on a prescribed medicine: some medicines are dosed around meals, and a change in diet can change how they work. 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.

Weight Watchers Diet safety at a glance

Weight Watchers Di... overall Use caution Generally safe for most healthy adults, but check with a clinician if you have health conditions or take medications.
Pregnancy Use caution Weight loss is usually not advised during pregnancy; speak with your doctor about appropriate nutrition.
Breastfeeding Use caution Calorie restriction may affect milk supply, so discuss any diet plan with your healthcare provider first.

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

Still wondering about combining Promethazine and Weight Watchers Diet? 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. Weight Watchers Diet has documented interactions with 1 drug class — the most serious being antidiabetes drugs (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

Weight Watchers Diet Does Interact With Other Medications

Weight Watchers Diet has 86 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 86 No known interaction 2,744 (incl. Promethazine)
Taking anything else?

Check Another of Your Medications Against Weight Watchers Diet

Covers the 2,830 medications we’ve checked against Weight Watchers Diet. 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 Weight Watchers Diet. 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 follow Weight Watchers Diet and take the medicine. 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. Weight Watchers Diet’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Weight Watchers Diet side to compare — that is a limit of the record, not a statement that Weight Watchers Diet has no side effects.

From our Q&A

Questions About Weight Watchers Diet 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 Weight Watchers Diet 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 Weight Watchers Diet 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 Weight Watchers Diet 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 Weight Watchers Diet
Steady interest

#1,085 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Promethazine
Steady interest

#2,141 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 Weight Watchers Diet reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Weight Watchers Diet 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 .
Eating pattern

About Weight Watchers Diet

What is Weight Watchers Diet?

  • Weight loss
  • Weight maintenance
  • Building healthier eating habits
  • Behavioral support for diet change
  • General wellness and lifestyle improvement

Weight Watchers (now called WW) is a commercial weight-loss program built around a points system, food tracking, and group or online support rather than a pill or herbal product. Research generally shows it can help people lose a modest amount of weight and keep some of it off, especially when combined with regular activity. Talk with your doctor or pharmacist before starting any weight-loss plan, particularly if you have a medical condition.

Not applicable (this is a commercial weight-management program, not a plant or supplement) · Structured eating plan with a points-based food system, app, group or online support, and coaching

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

Weight Watchers Diet: dosing

There is no pill or standardized dose for Weight Watchers, since it is a behavioral eating program. Instead, you follow the program's points budget and tracking system as set up in the app or plan you select.The right calorie or points target depends on your age, sex, weight, activity level, and goals, and the program personalizes this for you.

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

Read the full Weight Watchers Diet 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 & Weight Watchers Diet

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

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

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Weight Watchers Diet page.

No interaction 2,743 drugs checked — show the list

We also checked Weight Watchers Diet 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 Weight Watchers Diet list.

See the full Weight Watchers Diet interactions page
See every supplement checked against Promethazine, ranked by severity
Evidence & sources

Weight Watchers Diet References

The 1 references that drive our Weight Watchers Diet 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. O'Neil PM, Miller-Kovach K, Tuerk PW, et al. Randomized controlled trial of a nationally available weight control program tailored for adults with type 2 diabetes. Obesity (Silver Spring). 2016;24(11):2269-2277. 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

Following Weight Watchers Diet While Taking Promethazine: Common Questions

Is it safe to follow Weight Watchers Diet while taking Promethazine?
We do not list a known interaction between Weight Watchers Diet 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 Weight Watchers Diet and Promethazine combination checked?
Interactions in our licensed database are recorded against drug classes. Promethazine is filed under 4 classifications, and Weight Watchers Diet 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 Weight Watchers Diet interact with any other medications?
Yes. Weight Watchers Diet 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 — Weight Watchers Diet 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

Weight Watchers Diet 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 1 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Promethazine and Weight Watchers Diet?

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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.