promethazine (cont.)
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.
There may be an increase in the risk of certain neurologic reactions that
affect movement of muscles (EPS, see below) when promethazine is combined with
medicines that also cause EPS. Such drugs include antipsychotics, metoclopramide
(Reglan), and amoxapine (Asendin).
Promethazine should not be used with propylthiouracil (PTU) due to the
increased risk of low white blood cell counts and increased risk of infections.
The reason for this interaction is not known.
Concurrent use of promethazine with the dye used for myelography (x-rays of
the spinal cord) can lower the threshold for
seizures and thus increase the risk
of seizures. Promethazine should be stopped at least 48 hours before myelography
and not restarted until at least 24 hours after myelography.
PREGNANCY: There are no adequate studies of promethazine in
pregnant
women. Administration of promethazine within 2 weeks of delivery may affect
platelet function in the newborn.
NURSING MOTHERS: It is not known whether promethazine is excreted in
breast-milk.
SIDE EFFECTS: Promethazine often causes sedation. 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. Promethazine also causes anticholinergic side
effects such as blurred vision, dry mouth, dilated pupils, nausea, urinary
retention (inability to urinate), impotence, and constipation.
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 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
severe 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 missed menstrual periods, breast enlargement or
tenderness, loss of sexual drive, impotence,
inability to ejaculate, and
priapism. Weight gain also may occur.
Reference: FDA Prescribing Information
Last Editorial Review: 10/21/2008
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
- Drug Interactions - Learn about potential drug interactions you may be exposed to. Drug interactions can occur with prescription drugs, OTC medication, vitamins, herbs, and supplements.
- Nausea and Vomiting - Nausea and vomiting symptoms of many conditions including motion sickness, pregnancy, emotional stress, gallbladder disease, and more. Learn how to recognize the warning signs of nausea and vomiting on MedicineNet.com
- Drugs: What You Should Know About Your Drugs - Find out what you should know about your drugs such as side effects, warnings and precautions, storage information, and if a generic version is as good as the brand name.
Latest Medical News
Back to Medications Index