Phenergan: Expert Relief for Nausea, Allergies, and Motion Sickness

Phenergan

Product dosage: 25mg
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Synonyms Fenazin Histerzin Lergigan Procodin Prometazina Fenergan Promethazin Psicosoma Anergan Phenerex Prothiazine Anvomin Pamergan Tixylix Proneurin Fenazine Promethacon Pyrethia Romergan V-gan Tixylix linctus Prorex Avomine Histazin Shogan Prozin Closin Lenazine Prohist Pipolphen Fargan Antiallersin Promethegan Insomn-eze Frinova Prothazin Histantil Promodin Titanox Promadryl Diprazinum Histaloc Allersoothe Farganesse Phenadoz Vegetamin a Histabil Proazamine chloride Promethazinum Phenerzine Hiberna Promezin Prothazine Promacot Promergan Phergan Nufapreg Fenazil Synvomin Atosil Otosil Diphergan Lilly Receptozine Promargan Polfergan Show more

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Phenergan (promethazine hydrochloride) is a versatile prescription medication belonging to the phenothiazine class of drugs, primarily recognized for its potent antihistaminic, antiemetic, and sedative properties. Developed for clinical efficacy, it works by blocking histamine H1 receptors in the brain and periphery, mitigating allergic responses, nausea, and vomiting. Its central action also provides calming effects, making it a trusted choice in both outpatient and inpatient settings under appropriate medical supervision. This product card provides a comprehensive, expert-level overview intended for healthcare professionals and informed patients.

Features

• Active Ingredient: Promethazine hydrochloride
• Available Forms: Tablets (12.5 mg, 25 mg, 50 mg), syrup (6.25 mg/5 mL, 25 mg/5 mL), suppositories (12.5 mg, 25 mg), injectable solution (25 mg/mL, 50 mg/mL)
• Pharmacological Class: First-generation antihistamine (H1 receptor antagonist) with antiemetic, sedative, and anticholinergic properties
• Onset of Action: Oral: ~20 minutes; IV/IM: ~5–10 minutes; duration of effect typically 4–6 hours, though sedation may persist longer
• Prescription Status: Rx-only in most jurisdictions
• Manufacturer Variations: Available as branded (Phenergan) and generic formulations

Benefits

• Provides rapid and effective relief from moderate to severe nausea and vomiting, including postoperative, chemotherapy-induced, or vertigo-related symptoms.
• Effectively manages allergic conditions such as hay fever, urticaria, and angioedema by inhibiting histamine-mediated responses.
• Alleviates motion sickness with proven efficacy, making it suitable for travel-related nausea prevention.
• Induces sedation useful for preoperative anxiolysis, adjunctive anesthesia, or managing restlessness and agitation.
• Offers flexible administration routes (oral, rectal, parenteral) to accommodate varying clinical scenarios and patient needs.
• Cost-effective due to widespread availability in generic form, ensuring accessibility.

Common use

Phenergan is commonly prescribed for the prevention and treatment of nausea and vomiting associated with anesthesia, surgery, chemotherapy, radiation therapy, or motion sickness. It is also indicated for allergic conditions including seasonal and perennial allergic rhinitis, allergic conjunctivitis, and mild allergic skin reactions. Off-label, it is sometimes used for sedation, as an adjunct to analgesics for pain management (e.g., with opioids postoperatively), and for treating insomnia or agitation when other agents are unsuitable. Its use should always be guided by a healthcare provider considering individual patient factors.

Dosage and direction

Dosage must be individualized based on indication, patient age, medical history, and route of administration. Below are general adult guidelines; pediatric and geriatric dosing requires careful adjustment and medical oversight.

• For nausea/vomiting (adults): Oral/rectal: 12.5–25 mg every 4–6 hours as needed. IM/IV: 12.5–25 mg; may repeat every 4–6 hours. Maximum daily dose should not exceed 100 mg in divided doses unless under close supervision.
• For allergy symptoms (adults): 12.5 mg at bedtime or 6.25–12.5 mg three times daily; maximum 25 mg per dose.
• For motion sickness (adults): 25 mg taken 30–60 minutes before travel; may repeat 8–12 hours later if needed.
• For sedation (adults): 25–50 mg orally or IM at bedtime or preoperatively.

Administration notes: Tablets may be taken with or without food. Shake syrup well before use. Avoid intra-arterial injection due to risk of severe tissue injury. IV administration should be slow, diluted, and given through a secure line. Do not administer subcutaneously.

Precautions

• Use with caution in patients with respiratory conditions (e.g., asthma, COPD, sleep apnea) due to potential respiratory depression.
• Avoid in patients with narrow-angle glaucoma, prostatic hypertrophy, or bladder neck obstruction due to anticholinergic effects.
• May impair mental and physical abilities; advise against driving or operating machinery until effect is known.
• Risk of drowsiness is increased with alcohol or other CNS depressants; concomitant use should be avoided.
• Elderly patients are more susceptible to sedative, anticholinergic, and hypotensive effects; use lower doses and monitor closely.
• Prolonged use may lead to tolerance or dependence; use the lowest effective dose for the shortest duration.
• In pediatric patients, avoid use in children under 2 years due to risk of fatal respiratory depression.

Contraindications

• Known hypersensitivity to promethazine, other phenothiazines, or any component of the formulation.
• Comatose states or significantly depressed level of consciousness.
• Use in neonates or infants younger than 2 years of age.
• Concurrent use with MAO inhibitors (risk of hyperthermia, hypertension, seizures).
• Suspected or established subcortical brain damage.
• History of sleep apnea or severe respiratory impairment.

Possible side effect

Common side effects include:

• Drowsiness, sedation, dizziness
• Dry mouth, blurred vision
• Hypotension, tachycardia
• Fatigue, confusion (especially in elderly)
• Gastrointestinal disturbances (e.g., constipation)

Less common but serious side effects requiring medical attention:

• Extrapyramidal symptoms (e.g., dystonia, akathisia)
• Neuroleptic malignant syndrome (hyperthermia, muscle rigidity, autonomic instability)
• Severe respiratory depression
• Blood dyscrasias (e.g., agranulocytosis, leukopenia)
• Jaundice or hepatic dysfunction
• Seizures
• Tissue injury with improper IV/IM administration (e.g., gangrene, thrombophlebitis)

Drug interaction

• CNS depressants (e.g., opioids, benzodiazepines, alcohol): Enhanced sedative and respiratory depressant effects.
• Anticholinergics (e.g., atropine, tricyclic antidepressants): Additive anticholinergic effects (e.g., dry mouth, urinary retention).
• MAO inhibitors: Risk of severe hypertension, hyperpyrexia, convulsions; avoid concomitant use.
• Epinephrine: May reverse pressor effect; use norepinephrine if vasopressor needed.
• Drugs prolonging QT interval (e.g., certain antipsychotics, antiarrhythmics): Potential additive effect on QT prolongation.
• Lithium: May enhance neurotoxicity.

Missed dose

If a dose is missed, take it as soon as remembered unless it is nearly time for the next dose. Do not double the dose to catch up. For as-needed use (e.g., nausea), take when symptoms occur, respecting the minimum interval between doses (typically 4–6 hours). For regular dosing, resume the normal schedule.

Overdose

Overdose may manifest as severe CNS depression (ranging from drowsiness to coma), hypotension, respiratory depression, anticholinergic symptoms (e.g., dry mouth, fixed dilated pupils), agitation, hallucinations, or convulsions. Cardiovascular collapse may occur. Treatment is supportive and symptomatic: ensure airway patency, administer activated charcoal if ingestion recent, monitor vital signs, and consider IV fluids for hypotension. Avoid stimulants; benzodiazepines may be used for seizures. There is no specific antidote. Seek immediate medical attention.

Storage

Store at room temperature (15–30°C or 59–86°F). Protect from light and moisture. Keep oral formulations tightly closed. Do not freeze. Keep out of reach of children and pets. Do not use beyond the expiration date. Discard unused portions of oral solution after intended treatment course.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis, treatment decisions, and personalized dosing. Do not initiate, adjust, or discontinue Phenergan without medical supervision. The manufacturer and provider of this information are not liable for any adverse outcomes resulting from use or misuse.

Reviews

Clinical and patient perspectives often highlight Phenergan’s efficacy in controlling refractory nausea and providing sedation. However, reviews caution regarding sedation intensity and potential for extrapyramidal symptoms in sensitive individuals. Many experts emphasize its value in specific scenarios but advise cautious patient selection and dosing, particularly in pediatrics and geriatrics.