Comprehensive medication guide to Promethazine including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$15 copay for generic tablets; Tier 1 on most commercial and Medicare Part D plans, no prior authorization typically required. Brand-name suppositories may be Tier 2–3 with higher copays.
Estimated Cash Pricing
$20–$30 retail for generic 25 mg tablets (30-count); as low as $4.68–$7.99 with GoodRx or SingleCare coupons for a 30-day supply. Brand-name suppositories (Phenadoz, Promethegan) cost approximately $120 retail; ~$26 with GoodRx.
Medfinder Findability Score
72/100
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Promethazine is a first-generation antihistamine and phenothiazine derivative with over 70 years of clinical use. Previously sold under the brand name Phenergan (now discontinued), it remains widely prescribed in generic form. Brand-name suppositories (Phenadoz and Promethegan) are still available.
Promethazine is FDA-approved for allergic conditions (runny nose, hives, itching, allergic conjunctivitis), nausea and vomiting from motion sickness or surgery, motion sickness prevention, and sedation before or after surgical procedures. It is also used off-label for nausea and vomiting during pregnancy, migraine-associated nausea, and as a mild sleep aid.
Promethazine comes in oral tablets (12.5 mg, 25 mg, 50 mg), oral syrup (6.25 mg/5 mL), rectal suppositories (12.5 mg, 25 mg), and injectable formulations (hospital use only). It is not a controlled substance, can be prescribed by any licensed provider, and is eligible for multiple refills.
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Promethazine works through a multi-receptor mechanism that explains its diverse therapeutic applications. Its primary action is as an H1 histamine receptor antagonist — blocking histamine prevents the allergic response (runny nose, itching, hives). Because promethazine readily crosses the blood-brain barrier, it also blocks H1 receptors in the central nervous system, causing significant sedation.
Its antiemetic (anti-nausea) effect comes from blocking D2 dopamine receptors in the brain's chemoreceptor trigger zone (CTZ) — the area that initiates the vomiting reflex. By blocking this signal, promethazine reduces nausea and prevents vomiting across multiple causes.
Additionally, promethazine has strong anticholinergic properties (blocking acetylcholine receptors in the vestibular system) which make it highly effective for motion sickness — more effective than most other antihistamines. It also blocks alpha-adrenergic receptors, contributing to sedation and potential side effects like orthostatic hypotension.
12.5 mg — tablet
Lowest oral tablet dose; used for allergies and mild nausea
25 mg — tablet
Most common oral dose for nausea, motion sickness, and allergies
50 mg — tablet
Higher dose used for sedation and severe nausea; typically bedtime use
6.25 mg/5 mL — oral syrup
Liquid form for children and adults who can't swallow tablets
12.5 mg — rectal suppository
Suppository for patients unable to take oral medication due to vomiting
25 mg — rectal suppository
Standard suppository dose for nausea and vomiting; brand names: Phenadoz, Promethegan
25 mg/mL — injection (hospital only)
Injectable form for clinical settings; currently in active shortage
50 mg/mL — injection (hospital only)
Higher-concentration injectable; currently in active shortage
Oral promethazine tablets and syrup are generally available at most retail pharmacies in 2026 and are not listed in any active FDA or ASHP national shortage. However, promethazine hydrochloride injection (25 mg/mL and 50 mg/mL ampules) is in an active ASHP-listed shortage, affecting hospital and clinical settings — not outpatient pharmacies.
Rectal suppositories may need to be specially ordered at some pharmacies since they are stocked less routinely than tablets. Individual pharmacies can occasionally run out of tablets due to localized supply gaps, even though the drug is not in national shortage. Patients may need to check 2-3 pharmacies to find their specific form and strength.
If you're having trouble locating promethazine at your usual pharmacy, medfinder calls pharmacies near you to find which ones can fill your prescription, and delivers results by text — no hold music, no runaround.
Because promethazine is not a DEA-scheduled controlled substance, any licensed prescriber can prescribe it without special DEA authority or restricted prescriber registration. There are no federal limits on how many refills can be authorized.
Telehealth providers can also prescribe promethazine in all 50 states via video or phone consultation, with no in-person visit required. Platforms such as Teladoc, MDLive, Amazon Clinic, and urgent care telehealth services can prescribe oral promethazine for nausea, allergies, and motion sickness.
No. Promethazine by itself is not a DEA-scheduled controlled substance in the United States. It can be prescribed by any licensed provider (including via telehealth), called in to a pharmacy by phone, and filled with unlimited refills as authorized by the prescriber. There are no federal quantity limits or special prescription requirements.
Important distinction: Promethazine combined with codeine (promethazine-codeine syrup) is a different product. Codeine is a Schedule V controlled substance in some states and a Schedule III in others. Combination products have prescription restrictions that plain promethazine does not.
The most common side effects of promethazine include:
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Ondansetron (generic Zofran)
Serotonin 5-HT3 antagonist; equally effective for nausea with significantly less sedation; preferred for postoperative and chemotherapy-induced nausea; widely available as low-cost generic
Meclizine (Antivert, Bonine)
First-generation antihistamine approved for motion sickness and vertigo; available OTC; less drowsy than promethazine; good alternative for travel nausea
Metoclopramide (generic Reglan)
Dopamine antagonist and prokinetic; effective for gastroparesis-related nausea; shorter-term use preferred due to tardive dyskinesia risk with prolonged use
Prochlorperazine (generic Compazine)
Same phenothiazine class as promethazine; less sedating but higher extrapyramidal reaction risk; commonly used in emergency settings for severe nausea
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Opioid pain medications (morphine, oxycodone, codeine, fentanyl)
majorMajor interaction: combined CNS and respiratory depression. Opioid doses should be reduced by 25-50% when used with promethazine.
MAO Inhibitors (phenelzine, tranylcypromine, selegiline)
majorMajor interaction: prolonged and intensified anticholinergic and CNS effects. Avoid combination; MAOIs remain active 2 weeks after stopping.
Epinephrine
majorPromethazine reverses epinephrine's vasopressor effect via alpha-adrenergic blockade. Do not use epinephrine to treat promethazine-induced hypotension.
CNS Depressants (benzodiazepines, barbiturates, sleep aids, alcohol)
majorModerate-major: additive sedation and respiratory depression. Reduce doses and monitor closely when combined.
Tricyclic antidepressants (amitriptyline, nortriptyline)
moderateModerate: additive anticholinergic burden. Increased risk of confusion, dry mouth, urinary retention, especially in elderly.
QT-prolonging drugs (ondansetron, azithromycin, fluoroquinolones)
moderateModerate: combined QT prolongation risk. Use with caution in patients with cardiac arrhythmia history.
Anticonvulsants (seizure medications)
moderateModerate: promethazine lowers seizure threshold; may complicate seizure control. Also additive sedation with CNS depressant anticonvulsants.
Promethazine is a time-tested, affordable, and versatile medication with more than seven decades of clinical use. As a generic with no manufacturer patient assistance program needed — because it's already so inexpensive — it represents one of the more accessible prescription options for patients managing nausea, allergies, motion sickness, or perioperative sedation needs.
The active injectable shortage in 2026 affects hospitals and surgical centers, not outpatient pharmacies. Oral tablets and suppositories remain available, though individual pharmacies may occasionally run short. Patients are advised to use discount coupons (GoodRx, SingleCare) to minimize costs, and to plan refills ahead to avoid gaps in availability.
If you're struggling to locate promethazine at your pharmacy, medfinder calls pharmacies near you to find which ones can fill your prescription, delivering results by text. No hold music, no runaround — just answers.
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Our medication guides are researched and written to help patients make informed decisions. All content is reviewed for accuracy and updated regularly. Learn more about our standards
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