What it's used for
Promethazine hydrochloride tablets are used to treat perennial and seasonal allergic rhinitis, vasomotor rhinitis, and allergic conjunctivitis due to food or inhalant allergens.
Source: U.S. FDA-approved prescribing information (openFDA).
Typical dosing
The average oral adult dose is 25 mg taken before retiring, though 12.5 mg may be taken before meals and at bedtime if needed.
Dosing shown here is the general FDA-labeled range. Your prescribing clinician determines the exact dose, form, and schedule for you — this is not a substitute for medical advice.
Boxed warning / key safety info
This medication should not be used in children under 2 years of age because of the risk of fatal respiratory depression.
Common side effects
Drowsiness is the most prominent central nervous system effect, along with sedation, blurred vision, dizziness, and confusion.
Covered strengths on the Tab $0 list
Covered at $0 with an active Tab membership when filled at a participating pharmacy nationwide or through mail order. A licensed clinician must prescribe the medication.
Related medications
Other allergy, cough & cold medications covered at $0 with an active Tab membership.
Promethazine cost without insurance
Cash prices for Promethazine without insurance vary widely by pharmacy, strength and quantity — the same prescription can cost very different amounts at two pharmacies in the same town. That is the problem a membership solves.
Promethazine is on Tab's covered $0 generic list. With an active Tab membership, every covered strength is $0 — not a percentage off, not a coupon that changes month to month — at participating pharmacies nationwide or through mail order. You do not need insurance, and Tab works whether or not you have a health plan.
Tab is a membership, not insurance. Covered medications require a prescription from a licensed clinician.
Promethazine dosage and administration
Promethazine HCl Suppositories are contraindicated for children under 2 years of age (see WARNINGS - Black Box Warning and Use in Pediatric Patients ). Promethazine HCl Suppositories are for rectal administration only. Allergy - The average dose is 25 mg taken before retiring; however, 12.5 mg may be taken before meals and on retiring, if necessary. Single 25 mg doses at bedtime or 6.25 to 12.5 mg taken three times daily will usually suffice. After initiation of treatment in children or adults, dosage should be adjusted to the smallest amount adequate to relieve symptoms. The administration of promethazine hydrochloride in 25 mg doses will control minor transfusion reactions of an allergic nature. Motion Sickness - The average adult dose is 25 mg taken twice daily.
Excerpt from the FDA-approved prescribing information (openFDA), retrieved 2026-09-15. Your prescribing clinician decides the exact dose, form and schedule for you — this is not medical advice.
Promethazine side effects
Central Nervous System - Drowsiness is the most prominent CNS effect of this drug. Sedation, somnolence, blurred vision, dizziness; confusion, disorientation, and extrapyramidal symptoms such as oculogyric crisis, torticollis, and tongue protrusion; lassitude, tinnitus, incoordination, fatigue, euphoria, nervousness, diplopia, insomnia, tremors, convulsive seizures, excitation, catatonic-like states, hysteria and hallucinations have also been reported. Cardiovascular - Increased or decreased blood pressure, tachycardia, bradycardia, faintness. Dermatologic - Dermatitis, photosensitivity, urticaria. Hematologic - Leukopenia, thrombocytopenia, thrombocytopenic purpura, agranulocytosis. Gastrointestinal - Dry mouth, nausea, vomiting, jaundice.
Excerpt from the FDA-approved prescribing information (openFDA), retrieved 2026-09-15. This is not a complete list. Report side effects to your clinician, and seek care for anything severe or unexpected.
Promethazine drug interactions
CNS Depressants - Promethazine HCl Suppositories may increase, prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; therefore, such agents should be avoided or administered in reduced dosage to patients receiving promethazine HCl. When given concomitantly with Promethazine HCl Suppositories, the dose of barbiturates should be reduced by at least one-half, and the dose of narcotics should be reduced by one-quarter to one-half. Dosage must be individualized. Excessive amounts of promethazine HCl relative to a narcotic may lead to restlessness and motor hyperactivity in the patient with pain;
Excerpt from the FDA-approved prescribing information (openFDA), retrieved 2026-09-15. Tell your clinician and pharmacist about every medication, supplement and over-the-counter product you take.
Who should not take promethazine
Promethazine HCl Suppositories are contraindicated for use in pediatric patients less than two years of age. Promethazine HCl Suppositories are contraindicated in comatose states, and in individuals known to be hypersensitive or to have had an idiosyncratic reaction to promethazine or to other phenothiazines. Antihistamines are contraindicated for use in the treatment of lower respiratory tract symptoms including asthma.
Excerpt from the FDA-approved prescribing information (openFDA), retrieved 2026-09-15. Whether this medication is appropriate for you is a clinical decision made by your prescribing clinician.
Common questions
Is promethazine covered at $0 with Tab?
Yes. Promethazine is on Tab's covered $0 generic list — every covered strength is $0 with an active membership, at participating pharmacies nationwide or by mail order.
Do I need insurance to get promethazine through Tab?
No. Tab is a membership, not insurance. Covered medications are $0 with an active membership whether or not you have a health plan.
How do I get a promethazine prescription with Tab?
Book a video visit with a licensed Tab clinician (unlimited visits are included with membership). If it's clinically appropriate, they send the prescription to your chosen participating pharmacy or by mail order.
How much does promethazine cost without insurance?
Without insurance, retail cash prices for promethazine vary by pharmacy, strength and quantity. Promethazine is on Tab's covered $0 generic list, so every covered strength is $0 with an active Tab membership at participating pharmacies nationwide or by mail order.
What is the cheapest way to get promethazine?
For medications on Tab's covered list, a Tab membership is the cheapest route: covered strengths of promethazine are $0 with an active membership, and unlimited video visits with a licensed clinician are included, so the visit that produces the prescription is covered too.
What is the usual dose of promethazine?
Promethazine HCl Suppositories are contraindicated for children under 2 years of age (see WARNINGS - Black Box Warning and Use in Pediatric Patients ). Promethazine HCl Suppositories are for rectal administration only. Allergy - The average dose is 25 mg taken before retiring; however, 12.5 mg may be taken before meals and on retiring, if necessary. (FDA-approved label, retrieved 2026-09-15. Your clinician sets your dose.)
What are the side effects of promethazine?
Central Nervous System - Drowsiness is the most prominent CNS effect of this drug. Sedation, somnolence, blurred vision, dizziness; confusion, disorientation, and extrapyramidal symptoms such as oculogyric crisis, torticollis, and tongue protrusion; (FDA-approved label, retrieved 2026-09-15.)
What interacts with promethazine?
CNS Depressants - Promethazine HCl Suppositories may increase, prolong, or intensify the sedative action of other central-nervous-system depressants, such as alcohol, sedatives/hypnotics (including barbiturates), narcotics, narcotic analgesics, general anesthetics, tricyclic antidepressants, and tranquilizers; (FDA-approved label, retrieved 2026-09-15. Tell your clinician about every medication and supplement you take.)
Promethazine is $0 on the covered list
Members pay $0 for covered generics at participating pharmacies nationwide or by mail order — plus unlimited virtual primary care, urgent care and dermatology visits. No insurance needed.
Solo $49/mo · Family $119/mo for up to 4 people · Family+ $149/mo for up to 8
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