Promethazine: Allergy Uses, Side Effects and Dosing (original) (raw)

What are the side effects of promethazine?

Promethazine causes sedation, confusion, and disorientation. In children less than two it can depress respiration and lead to death. Therefore, it should not be used in children less than two years old. Dizziness may also occur. Ironically, promethazine sometimes stimulates patients, particularly children. Such stimulation may be manifest by restlessness, inability to sleep, heart palpitations or even seizures.

Other side effects include anticholinergic side effects such as:

Extrapyramidal symptoms (EPS) may occur. EPS are categorized as dystonic reactions (alterations in muscle tone), sharp, involuntary muscle movements (often limited to one muscle or muscle group), akathisia (subjective restlessness), and Parkinsonism. Parkinsonian symptoms are more common in older persons whereas children more often develop involuntary muscle movement reactions. Dystonic reactions are most commonly seen during the first week of treatment. Restlessness and Parkinsonian symptoms usually develop days to weeks after starting therapy.

A serious complex called neuroleptic malignant syndrome (NMS) can occur in patients receiving phenothiazines. NMS consists of high body temperature, severe EPS, changes in consciousness and mental status, and increased heart rate with low or high blood pressure. NMS occurs more frequently in young men and in persons who are dehydrated.

Rarely, blood cell disorders can occur; low white cell counts can lead to infections.

Phenothiazines such as promethazine can cause skin hyperpigmentation (darkening) but usually only after prolonged use. The effect usually is restricted to areas of the body exposed to sunlight. Thus, people who need long-term treatment with promethazine should either keep out of the sun or use effective sunscreens.

Phenothiazines can cause blurred vision, difficulty with nighttime vision, or changes in color vision.

Liver damage has been reported rarely with phenothiazines. Jaundice is possible. Jaundice also may occur in newborns of mothers who receive phenothiazines during pregnancy.

Phenothiazines such as promethazine block dopamine receptors. This effect can lead to increases in blood levels of prolactin, a hormone involved in lactation (formation of breast milk). As a result, phenothiazines can cause the breast to produce fluid ("milk") even when a woman is not pregnant.

Additionally, phenothiazines can cause: