promethazine, Phenergan (Discontinued brand), Phenadoz, Promethegan (cont.)

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STORAGE: Tablets, syrup and injection should be stored at room temperature, between 15 C to 25 C (68 F to 77 F). Suppositories should be stored at 2 C to 8 C (36 F to 46 F).

PRESCRIBED FOR: Promethazine is prescribed for treating nausea or vomiting, motion sickness, and allergic reactions and for sedation prior to or after surgery.


  • Allergic reactions are treated with 6.25-25 mg orally 3 times daily. A single 25 mg dose administered at bedtime also may suffice. A 25 mg injection is also used.
  • Nausea and vomiting may be managed with 12.5-25 mg administered orally by injection every 4-6 hours as needed.
  • Doses of 25-50 mg by injection are used for sedation before or after surgery.
  • For prevention of motion sickness, 25 mg is used 30 to 60 minutes before the motion begins and then every 8 to 12 hours as needed. Oral, rectal and injectable doses are similar.
  • Promethazine injections are used when the oral route is not possible (for example, with severe vomiting).
  • Tablets may be taken with or without food.
  • Suppositories are unwrapped and moistened with water before insertion into the rectum. If the suppository is too soft from being stored in a warm place, it may be chilled in the refrigerator for 20 to 30 minutes or placed in cold water before the wrapper is removed.

DRUG INTERACTIONS: Promethazine should not be taken with any of the MAO (mono-amine oxidase) inhibitor-class of antidepressants, for example, isocarboxazid (Marplan), phenelzine (Nardil), tranylcypromine (Parnate), and procarbazine (Matulane), because of the increased risk of extrapyramidal symptoms (EPS)--uncontrollable movement disorders.

Excessive anti-cholinergic effects (described below) can occur when promethazine is used with other antihistamines, for example, diphenhydramine (Benadryl); some phenothiazines, for example, thioridazine (Mellaril); some tricyclic antidepressants, for example, amitriptyline (Elavil), clozapine (Clozaril), cyclobenzaprine (Flexeril), and disopyramide (Norpace).

Excessive sedation may occur when promethazine is combined with other medications that depress the central nervous system (brain) and cause sedation. Such drugs include ethanol, barbiturates, anti-anxiety medications, sedatives, other phenothiazines, and narcotic pain medications. Promethazine should not be combined with amiodarone (Cordarone), sotalol (Betapace), pimozide (Orap), quinidine, and procainamide because of an increased risk of abnormal heart beats.

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