What Is Phenergan? Uses, Dosage, and What You Need to Know in 2026

Phenergan is a brand name for promethazine hydrochloride, a first-generation antihistamine that has been used in the United States since 1951. It belongs to the phenothiazine drug class and works across multiple receptor systems to treat a wide range of conditions — from nausea to allergies to sedation. While the original Phenergan brand has been discontinued, generic promethazine remains widely prescribed today.

What Is Phenergan (Promethazine) Used For?

The FDA has approved promethazine for the following conditions:

Nausea and vomiting — Including post-operative nausea, nausea from motion sickness, and nausea in pregnancy (though off-label in the US for this use)

Motion sickness — Prevention and treatment of nausea, vomiting, and dizziness related to travel

Allergic conditions — Perennial and seasonal allergic rhinitis, allergic conjunctivitis, hives (urticaria), allergic reactions to blood products or dermatologic reactions

Pre- and post-operative sedation — Reducing anxiety and inducing sedation before or after surgical procedures

Adjunct to analgesia — Used in combination with reduced doses of analgesics for pain management in surgical settings

What Forms Does Phenergan Come In?

Promethazine is available in multiple dosage forms, which is one of its advantages — especially when a patient cannot keep oral medication down:

Oral tablets: 12.5 mg, 25 mg, and 50 mg — most commonly prescribed form

Oral solution/syrup: 6.25 mg/5 mL — easier for patients who have difficulty swallowing tablets

Rectal suppositories: 12.5 mg and 25 mg — ideal when vomiting prevents oral administration; available as Promethegan brand or generic

Injection (IM only): 25 mg/mL and 50 mg/mL — administered by healthcare providers in clinical settings; IV administration is strongly discouraged due to tissue injury risk

What Is the Typical Promethazine Dose?

Dosing varies by condition and patient age. Always follow your prescriber's instructions:

Nausea and vomiting (adults): 12.5–25 mg every 4–6 hours as needed

Motion sickness (adults): 25 mg taken 30–60 minutes before travel; may repeat in 8–12 hours if needed

Allergies (adults): 25 mg at bedtime; or 6.25–12.5 mg three times daily

Sedation before procedures (adults): 25–50 mg the evening before or as directed

Children (2 years and older): Dose is determined by weight (typically 0.5 mg/lb); always calculated by the prescriber. Never give to children under 2.

Is Phenergan (Promethazine) a Controlled Substance?

No. Promethazine is not a scheduled controlled substance under DEA regulations. This means:

Any licensed prescriber can write a prescription (no DEA special registration required)

Telehealth providers can prescribe it without restrictions that apply to scheduled drugs

Prescriptions can typically be called in to the pharmacy (not required to be in written form)

There are no mandatory refill restrictions based on controlled substance scheduling (though prescribers may still limit refills clinically)

Who Should Not Take Phenergan?

Promethazine is contraindicated in:

Children under 2 years of age (risk of fatal respiratory depression)

Patients with a known allergy to promethazine or phenothiazines

Patients with a history of sleep apnea (can worsen respiratory depression risk)

Patients with bone marrow suppression or severely compromised pulmonary function

Use with caution in: elderly patients (Beers Criteria), patients with seizure disorders, those with liver impairment, and anyone taking other CNS depressants.

Is Phenergan Hard to Find in 2026?

Yes. Promethazine is experiencing active supply disruptions in 2026, with the injectable form in the most severe shortage and oral tablets/suppositories experiencing limited availability. Use medfinder to find pharmacies near you with promethazine in stock. For a full explanation of why it's hard to find, see Why Is Phenergan So Hard to Find?.