- Nervous system disorders: sedation, dizziness, drowsiness, anxiety, psychomotor agitation, nightmares, increased nighttime apnea; rare: disorientation, confusion, extrapyramidal disorders, increased seizure activity (in children).
- Sensory organs: the promethazine causes accommodation and vision disorders, tinnitus or ringing in the ears.
- Cardiovascular system: orthostatic hypotension (when injected intravenously), decreased blood pressure, tachycardia or bradycardia.
- Digestive system: anesthesia of the oral mucosa, dry mouth (when administered orally), nausea, vomiting, cholestasis, constipation.
- Respiratory system: dryness in the nose and pharynx. Urinary system: rarely – difficult or painful urination.
- Laboratory parameters: rarely – leukopenia, thrombocytopenia, agranulocytosis.
- Allergic reactions: urticaria, dermatitis, asthma. Local reactions: when administered intramuscularly – painful infiltration at the injection site. Others: increased sweating, photosensitization.
Overdose. Symptoms: in children – agitation, anxiety, hallucinations, ataxia, athetosis, convulsions, mydriasis and fixed pupils, facial hyperemia, hyperthermia; then – vascular collapse, coma; in adults – lethargy, depression, coma; then – psychomotor agitation, convulsions.
Treatment: gastric lavage, oral administration of activated charcoal (when detoxifying early after oral administration of the drug); antiepileptic drugs, IVH and other resuscitation measures are indicated, dialysis is ineffective.
Increases the effect of narcotic analgesics, hypnotics, anxiolytics (tranquilizers) and antipsychotic drugs (neuroleptics), as well as drugs for general anesthesia, local anesthetics, m-cholinoblockers and hypotensive drugs (requires dose adjustment). It reduces the effect of amphetamine derivatives, m-cholinostimulants, anticholinesterase drugs, ephedrine, guanethidine, levodopa, dopamine. Barbiturates accelerate elimination and decrease activity. Beta-adrenoblockers increase (mutually) plasma concentrations (pronounced BP decrease, arrhythmias, irreversible retinopathy, tardive dyskinesia are possible).
It weakens the effect of bromocriptine and increases the serum concentration of prolactin.
Tricyclic antidepressants and anticholinergic drugs increase m-cholinoblocking activity, ethanol, clopheline, antiepileptic drugs – CNS depression.
MAO inhibitors (concomitant use is not recommended) and phenothiazine derivatives increase the risk of arterial hypotension and extrapyramidal disorders. Quinidine increases the likelihood of cardiodepressive effects. Myelotoxic drugs increase the manifestation of hematotoxicity of the drug.
During long-term treatment it is necessary to perform systematic general blood analysis and liver function evaluation. During further treatment, the degree of restriction shall be determined depending on individual tolerance.
Together with narcotic analgesics, anxiolytics – for complex preoperative preparation of patients, it is used under close medical supervision.
During treatment the use of ethanol is prohibited. Caution is required when administering parenteral high doses in the elderly because extrapyramidal disorders and acute urinary retention are possible.
The use of promethazine in children under 2 years of age may be accompanied by an increase in the frequency of nocturnal apnea attacks.
As an antiemetic drug should be used only in case of prolonged vomiting of known etiology.
Long-term use increases the risk of dental diseases (caries, periodontitis, candidiasis) due to reduced salivation.
Caffeine administration is recommended to prevent CNS depression. May mask the ototoxic effect (tinnitus and dizziness) of concomitantly used drugs. Increases the requirement for riboflavin. The solution is not suitable for intravenous and percutaneous administration.
Some dosage forms of promethazine contain sodium metabisulfite which may cause allergic reactions (including anaphylactoid) and bronchospasm.
Allergen skin scarification tests should be cancelled 72 h before allergy testing to prevent distorted results.
False positive pregnancy test results are possible during treatment.
During the initial, individually determined period of treatment, caution should be exercised when driving motor transport and engaging in other potentially dangerous activities that require increased concentration and rapid psychomotor reactions.