What is promethazine and codeine, and how does it work (mechanism of action)?
Promethazine is in a class of drugs called phenothiazines which also includes chlorpromazine,
and trifluoperazine; however, unlike the other drugs in this class, promethazine
is not used as an anti-psychotic but rather as an anti-histamine, sedative,
(anti-nausea), and cough suppressant.
Cells in the body release histamine during several types of allergic
reactions. When histamine binds to its receptors on other cells, it stimulates
changes within the cells that lead to release of other chemicals that cause
sneezing, itching, and
increased mucus production. Antihistamines such as promethazine compete with
histamine for one of the receptors for histamine (the H1 receptor) on cells;
however, when antihistamines bind to the receptors they do not stimulate the
cells. Instead, they prevent histamine from binding and stimulating the cells.
Promethazine also blocks the action of acetylcholine, a neurotransmitter that
nerves use to communicate with one another, on its receptors (anticholinergic
effect), and this may explain its benefit in reducing the
Codeine is a
weak narcotic pain-reliever and cough suppressant similar to morphine and
hydrocodone. In fact, a small amount of codeine is converted to morphine in the
body. The precise mechanism of action of codeine is not known; however, like
morphine, codeine binds to narcotic receptors in the brain (opioid receptors)
that are important for transmitting the sensation of pain throughout the body
and brain. Codeine increases tolerance to pain and decreases discomfort, but the
pain still is apparent to the patient. In addition to reducing pain, codeine
also causes sedation (drowsiness) and depresses breathing. The FDA approved
promethazine and codeine in January 1952.
What brand names are available for promethazine and codeine?
(Phenergan with Codeine: This brand no longer is available in the U.S.)
Is promethazine and codeine available as a generic drug?
GENERIC AVAILABLE: Yes
Do I need a prescription for promethazine and codeine?
What are the side effects of promethazine and codeine?
WARNING In children less than 6 years of age, promethazine and codeine can depress respiration and lead to death. Therefore, it should not be used in children less than 6 years old. Death has also been reported in children less than 2 years old due to respiratory depression. Although promethazine causes dizziness, it may stimulate activity in patients, particularly children. Such stimulation may be manifest by restlessness, inability to sleep, palpitations (rapid heartbeat) or even seizures.
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 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.
What is the dosage for promethazine and codeine?
The usual adult dose is one teaspoonful every 4 to 6
hours as needed. The maximum dose is two tablespoons daily.
Which drugs or supplements interact with promethazine and codeine?
Excessive sedation may occur when
promethazine and codeine is combined with other medications that cause sedation.
Such drugs include ethanol, barbiturates, anti-anxiety medications, sedatives,
other phenothiazines, and narcotic pain medications.
Promethazine should not be taken with any of the
oxidase (MAO) 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
diphenhydramine (Benadryl), some phenothiazines, for example, thioridazine,
some tricyclic antidepressants, for example,
(Clozaril, FazaClo, Versacloz),
(Active-Cyclobenzaprine, Amrix, EnovaRX-Cyclobenzaprine HCl, Fexmid)), and
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,
(Metozolv ODT, Reglan), and amoxapine.
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
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.
Which illness is known as a viral upper respiratory tract infection?
Is promethazine and codeine safe to take if I’m pregnant or breastfeeding?
There are no adequate studies of promethazine and
codeine in pregnant women. Administration of promethazine within two weeks of
delivery may affect platelet function in the newborn. Codeine generally is
pregnancy because it may cause fetal physical dependence, withdrawal and
It is not known if promethazine is excreted
in breast milk.
Small amounts of codeine are secreted in breast milk, but the risk of adverse
events in the infant is small.
What else should I know about promethazine and codeine?
What preparations of promethazine and codeine are available?
Syrup: 6.25mg of promethazine and 10mg of
codeine per teaspoonful.
How should I keep promethazine and codeine stored?
Promethazine and codeine should be stored at room
temperature, 15C – 25C (59F – 77F) in a tightly closed container protected from