Phenergan
Promethazine is a first-generation H1 receptor antagonist antihistamine and antiemetic medication. It is a prescription drug in the United States, but is available over the counter in the United Kingdom, Switzerland, and many other countries (brand names Phenergan, Promethegan, Romergan, Fargan, Farganesse, Prothiazine, Avomine, Atosil, RhinathioL).

Promethazine also has strong anticholinergic and sedative/hypnotic effects. Previously it was used as an antipsychotic, although it is generally not administered for this purpose now; promethazine has only approximately 1/10 of the antipsychotic strength of chlorpromazine.

Indications
As sedative/hypnotic
For preoperative sedation and to counteract postnarcotic nausea
As antiallergic medication to combat hay fever, allergic rhinitis, etc. To treat allergic reactions it can be given alone or in combination with oral decongestants like pseudo-ephedrine.
As an adjunct treatment for anaphylactoid conditions (IM/IV route preferred).
Together with codeine or dextromethorphan against cough
As a motion sickness or seasickness remedy when used with Ephedrine or Pseudoephedrine.
As an antipruritic (pruritus vulvae).
To combat moderate to severe morning sickness and hyperemesis gravidarum. In the UK promethazine is drug of first choice being preferred as an older drug with which there is a greater experience of use in pregnancy (second line being metoclopramide or prochlorperazine).[1] Whilst in the US, Zofran (ondansetron) is the usual drug of choice, though the high cost is prohibitive for some women.

Contraindications
Promethazine should not be given to children under two years of age; there is potential for fatal respiratory depression in this age group.[2]
Hypersensitivity to Phenothiazines
Closed angle glaucoma
Intoxication with alcohol or other central depressants
Severe hypotension or shock
Coma due to any reason
Severely impaired liver function
Urine hesitancy due to enlargement of the prostate gland

Side effects
Typical side effects are:

Blurred vision
Confusion in the elderly
Drowsiness, dizziness, fatigue, more rarely vertigo
Dry mouth
Seizures (extremely rare)
Neuroleptic malignant syndrome (extremely rare)
Respiratory depression in patients under age of 2 and in those with severely compromised pulmonal function
Constipation
Euphoria (very rare with high IV doses and/or coadministration with opioids/CNS depressants)
Restless legs.

Laboratory examinations
All patients should have their blood pressure measured frequently. During long-term therapy, blood cell counts, liver function studies, EKG, and EEG are recommended. The intervals should be determined according to the risk profile of the patient.

Recreational use
Promethazine is sometimes used as a recreational drug in conjunction with Codeine in prescription cough syrup. The mixture of Sprite and cough syrup with codeine, which is known as "purple drank" or "Sizzurp", is popularized in the rap world, especially in the Houston area. It is also sometimes used to counteract nausea caused by illicit opioid use. Promethazine is referred to as "zazz" on Baltimore streets, as in "let's get zazzed". This combination of drugs played a role in the death of rapper Pimp C, who had sung with Three 6 Mafia and Underground Kingz about mixing Promethazine and Codeine in the hit song "Sippin' On Some Sizzurp." Pimp C stopped breathing from an overdose of the mixture on December 4, 2007, he also suffered from Sleep Apnea which played a major role in his death. The combination of his breathing disorder and the shallow breathing the syrup causes proved to be a lethal combination.