The tablets are contra-indicated in patients who are hypersensitive to antihistamines or to any of the tablet ingredients.
The anticholinergic properties of chlorphenamine are intensified by monoamine oxidase inhibitors (MAOIs). The tablets are therefore contra-indicated in patients who have been treated with MAOIs within the last fourteen days.
Chlorphenamine, in common with other drugs having anticholinergic effects, should be used with caution in epilepsy; raised intra-ocular pressure including glaucoma; prostatic hypertrophy; severe hypertension or cardiovascular disease; bronchitis, bronchiectasis or asthma; hepatic impairment. Children and the elderly are more likely to experience the neurological anticholinergic effects and paradoxical excitation (eg. Increased energy, restlessness, nervousness).
The effects of alcohol may be increased and therefore concurrent use should be avoided
Should not be used with other antihistamine containing products, including antihistamine containing cough and cold medicines.
Patients with rare hereditary problems of galactose intolerance, Lapp lactase deficiency or glucose-galactose malabsorption should not take this medicine.
Keep out of sight and reach of children.
Concurrent use of chlorphenamine and hypnotics or anxiolytics may cause an increase in sedative effects, therefore medical advice should be sought before taking chlorphenamine concurrently with these medicines.
Chlorphenamine inhibits phenytoin metabolism and can lead to phenytoin toxicity.
The anticholinergic effects of chlorphenamine are intensified by MAOIs (see Contra-indications).
There are no adequate data from the use of chlorphenamine maleate in pregnant women. The potential risk for humans is unknown. Use during the third trimester may result in reactions in the newborn or premature neonates. Not to be used during pregnancy unless considered essentially by a physician.
Chlorphenamine maleate and other antihistamine may inhibit lactation and may be secreted in breast milk. Not to be used during lactation unless considered essential by a physician.
The anticholinergic properties of chlorphenamine may cause drowsiness, dizziness, blurred vision and psychomotor impairment, which can seriously hamper the patients' ability to drive and use machinery.
Specific estimation of the frequency of adverse events for OTC products is inherently difficult (particularly numerator data). Adverse reactions which have been observed in clinical trails and which are considered to be common (occurring in ≥1% to <10% of subjects) or very common (occurring in ≥10% of subjects) are listed below by MedDRA System Organ Class. The frequency of other adverse reactions identified during post-marketing use is unknown.
Unknown: haemolytic anaemia, blood dyscrasias
Unknown: allergic reaction, angioedema, anaphylactic reactions
Unknown: confusion*, excitation*, irritability*, nightmares*, depression
Very common: sedation, somnolence
Common: disturbance in attention, abnormal coordination, dizziness headache
Common: blurred vision
Unknown: palpitations, tachycardia, arrythmias
Unknown: thickening of bronchial secretions
Common: nausea, dry mouth
Unknown: vomiting, abdominal pain, diarrhoea, dyspepsia
Unknown: hepatitis, jaundice
Unknown: exfoliative dermatitis, rash, urticaria, photosensitivity
Unknown: muscle twitching, muscle weakness
Unknown: urinary retention
Unknown: chest tightness
* Children and the elderly are more likely to experience the neurological anticholinergic effects and paradoxical excitation (eg. increased energy, restlessness, nervousness).