Sominex Tablets

Summary of Product Characteristics Updated 31-Jan-2024 | Teva UK Limited

1. Name of the medicinal product


2. Qualitative and quantitative composition

Promethazine hydrochloride EP 20mg/tab

Excipient with known effect: Each 20mg tablet contains 276.00mg lactose monohydrate.

For the full list of excipients, see section 6.1.

3. Pharmaceutical form


4. Clinical particulars
4.1 Therapeutic indications

As a night-time sleep aid, for the correction of temporary disturbances of sleep pattern where there is difficulty in going to sleep or staying asleep, caused for example by specific dislocation of normal routine.

4.2 Posology and method of administration


For bedtime use only.

Adults: one tablet at bedtime. May be taken up to one hour after going to bed when sleep is difficult to achieve.

Paediatric population: Not to be given to children under the age of 16 years except on medical advice.

Elderly: the normal adult dose may be taken.

Method of administration

For oral administration

4.3 Contraindications

• Hypersensitivity to the active substance, phenothiazines or to any of the excipients listed in section 6.1.

• Patients taking MAOIs or within 14 days of taking MAOIs.

• Patients in coma or suffering from CNS depression of any cause.

4.4 Special warnings and precautions for use

Not to be used for more than 7 days without medical advice.

Promethazine hydrochloride may thicken or dry lung secretion and impair expectoration. Therefore it should be used with caution in patients with asthma or other respiratory disorders (eg bronchitis or bronchiectasis).

In patients with severe coronary artery disease, narrow angle glaucoma, epilepsy, urinary retention, prostatic hypertrophy, hepatic or renal impairment, cardiovascular problems or pyloro-duodenal obstruction the product should only be taken after consulting a doctor.

This product should be used with caution in patients with seizure disorders or in patients receiving medication which may affect the seizure threshold because of risk of convulsions.

Promethazine hydrochloride may mask the warning signs of ototoxicity caused by ototoxic drugs e.g. salicylates. It may also delay the early diagnosis of intestinal obstruction or raised intracranial pressure through the suppression of vomiting.

Neuroleptic malignant syndrome

As with neuroleptics, neuroleptic malignant syndrome (NMS) characterized by hyperthermia, extrapyramidal disorders, muscle rigidity, altered mental status, autonomic nervous instability and elevated CPK may occur with concomitant use with drugs known to cause NMS such as antipsychotics (see section 4.5). As this syndrome is potentially fatal, promethazine must be discontinued immediately and intensive clinical monitoring and symptomatic treatment should be initiated.

QT prolongation

Phenothiazine derivatives may potentiate QT interval prolongation which increases the risk of onset of serious ventricular arrhythmias of the torsade de pointes type, which is potentially fatal (sudden death). QT prolongation is exacerbated, in particular, in the presence of bradycardia, hypokalaemia, and acquired (i.e. drug induced) QT prolongation. If the clinical situation permits, medical and laboratory evaluations should be performed to rule out possible risk factors before initiating treatment with a phenothiazine derivative and as deemed necessary during treatment (see section 4.8).



Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this medicine.


This medicinal product contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially 'sodium-free'.

4.5 Interaction with other medicinal products and other forms of interaction

Promethazine hydrochloride may potentiate the action of alcohol and other centrally acting depressants such as sedatives (barbiturates), opiod analgesics, antipsychotics, anticonvulsants, hypnotics and anxiolytics. MAOIs may enhance the antimuscarinic effects of antihistamines.

Antihistamines have an added antimuscarinic effect with other antimuscarinic drugs such as atropine and tricyclic antidepressants. Promethazine may interfere with immunologic urine pregnancy tests to produce false positive or negative results.

Promethazine hydrochloride may interfere with immunological urine pregnancy tests to produce false-positive or false-negative results.

Promethazine hydrochloride should be discontinued at least 72 hours before the start of skin tests as it may inhibit the cutaneous histamine response thus producing false negative results.

Concomitant use with antipsychotics may increase possibility of neuroleptic malignant syndrome (NMS).

Concomitant use of alcohol should be avoided.

4.6 Fertility, pregnancy and lactation

The advice of a doctor should be sought before use.


Sominex should not be used in pregnancy unless the physician considers it essential. The use of Sominex is not recommended in the 2 weeks prior to delivery in view of the risk of irritability and excitement in the neonate.


Available evidence suggests that the amount excreted in milk is insignificant. However, there are risks of neonatal irritability and excitement.

4.7 Effects on ability to drive and use machines

This product causes drowsiness. Do not drive or operate machinery.

4.8 Undesirable effects

Blood and lymphatic system disorders

Agranulocytosis, leucopenia, thrombocytopenia. Blood dycrasias including haemolytic anaemia occur rarely.

Psychiatric disorders

Sedation, paradoxical reactions such as hyperexcitability and abnormal movements, drowsiness, confusion, disorientation, restlessness, insomnia, nightmares.

Nervous system disorders

Convulsive seizures, headache, psychomotor impairment, antimuscarinic effects (dry mouth, blurred vision, urinary retention). Dizziness and tremor are rare side effects. The frequency of occurrence of extrapyramidal effects is not known.

Eye disorders

Angle closure glaucoma occurs rarely.

Ear and labyrinth disorders


Heart rate and rhythm disorders

Palpitations, arrhythmias, (including QT prolongation and torsade de pointes).

Vascular disorders


Respiratory, thoracic and mediastinal disorders

Nasal stuffiness. Bronchospasm occurs rarely.

Gastrointestinal disorders

Nausea, vomiting, gastric irritation.

Hepatobiliary disorders

Jaundice occurs rarely.

Skin and subcutaneous tissue disorders

Photosensitivity. Angioedema, urticarial, pruritus and rashes occur rarely.

Musculoskeletal and connective tissue disorders

Muscle spasms and tic-like movements of the head and face.

General disorders and administration site conditions

Anaphylaxis occurs rarely. Tiredness, anorexia.

The elderly are particularly susceptible to the anticholinergic effects and confusion due to promethazine.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme Website: or search for MHRA Yellow Card in the Google Play or Apple App Store.

4.9 Overdose

Common features include:

nausea, vomiting, flushing, dilated pupils, dry mouth and tongue, hot dry skin, fever, sinus tachycardia, hypertension, ataxia, nystagmus, drowsiness, delirium, agitation and visual hallucinations.

Uncommon systemic features include:

myoclonic jerking, coma, convulsions, cardiac conduction abnormalities and dysrhythmias, cardiovascular collapse, paralytic ileus, urinary retention and cardiorespiratory depression.

Patients who have been unconscious may be hypothermic.

In cases of unintentional exposure:

Children may also experience combinations of excitation, ataxia, incoordination, athetosis and hallucinations.


Gastric lavage or activated charcoal is only recommended if the patient presents within 1 hour of ingestion of a potentially toxic amount.

Treatment is otherwise supportive with attention to maintenance of adequate respiratory and circulatory status. Convulsions should be treated with diazepam or other suitable anticonvulsants.

Forced diuresis, haemodialysis and haemoperfusion are of no value

5. Pharmacological properties
5.1 Pharmacodynamic properties

Pharmacotherapeutic group: R06A D02

Promethazine hydrochloride – sedative. The drug is an antihistamine with anticholinergic activity.

5.2 Pharmacokinetic properties

Promethazine hydrochloride is readily absorbed from the gastrointestinal tract, but undergoes extensive first pass metabolism in the liver. With only 25% of the oral dose reaching the systemic circulation unchanged. After oral therapy therapeutic effects are identifiable at 15-30 minutes and peak plasma concentrations at 2 to 3 hours. Estimates of terminal half-life in blood plasma have been quoted as 4-6 hours. It is extensively plasma protein bound. It is eliminated mainly as metabolites, predominantly by the faecal (via biliary) route, with <1% of the parent compound and CA 10% as the sulfoxide metabolite being excreted in the urine over a 72 hour period.

5.3 Preclinical safety data

None stated.

6. Pharmaceutical particulars
6.1 List of excipients

Lactose, maize starch, croscarmellose sodium, magnesium stearate.

6.2 Incompatibilities

None known.

6.3 Shelf life

60 months unopened.

6.4 Special precautions for storage


6.5 Nature and contents of container

Opaque blister strip of polyvinylchloride/polyvinylidine chloride. Backed with aluminium foil. Each strip contains 8 tablets. One or two strips are packed into each cardboard carton.

6.6 Special precautions for disposal and other handling


7. Marketing authorisation holder

Actavis Group PTC ehf

Reykjaví kurvegi 76-78

220 Hafnarfjordur


8. Marketing authorisation number(s)

PL 30306/0080

9. Date of first authorisation/renewal of the authorisation

Date of first authorisation: 6th September 2002

10. Date of revision of the text


Company Contact Details
Teva UK Limited

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+44 (0)207 540 7000

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