What are the common side effects of Decolgen forte (paracetamol, pseudoephedrine, and chlorpheniramine)?

Common Side Effects of Decolgen Forte

Decolgen Forte, containing paracetamol, pseudoephedrine, and chlorpheniramine, commonly causes drowsiness, dry mouth, insomnia, irritability, and elevated blood pressure/heart rate, with the antihistamine component (chlorpheniramine) primarily responsible for sedation and anticholinergic effects, while pseudoephedrine causes cardiovascular and CNS stimulation. 1

Antihistamine-Related Side Effects (Chlorpheniramine)

First-generation antihistamines like chlorpheniramine have significant potential to cause sedation, performance impairment, and anticholinergic effects. 1

• Drowsiness and sedation are the most common side effects, occurring in approximately 11.5% of patients taking antihistamines 1
• Anticholinergic effects include dry mouth (xerostomia), urinary retention, and constipation 1
• Cognitive impairment may occur without subjective perception by the patient, affecting performance even when drowsiness is not felt 1

Decongestant-Related Side Effects (Pseudoephedrine)

Pseudoephedrine acts as an α-adrenergic agonist causing systemic vasoconstriction, leading to cardiovascular and central nervous system stimulation. 1, 2

• Cardiovascular effects include elevated blood pressure (mean increase of 0.99 mmHg systolic), increased heart rate (2.83 beats/min increase), and palpitations 1, 2, 3
• Central nervous system effects include insomnia, irritability, restlessness, anxiety, and tremor 1, 3
• Loss of appetite is commonly reported 1, 3
• Urinary retention may occur, particularly in patients with bladder neck obstruction 1

Analgesic-Related Side Effects (Paracetamol)

• Hepatotoxicity is the primary concern with paracetamol, particularly at doses exceeding 4000-6000 mg daily 1
• Paracetamol is generally well-tolerated at therapeutic doses with minimal side effects 1

Combined Formulation Considerations

The combination of these three agents can produce additive adverse effects, particularly when combined with caffeine or other sympathomimetic drugs. 1, 4

• Concomitant caffeine use may produce additive effects including elevated blood pressure, insomnia, irritability, and palpitations 1, 2
• Combining multiple sympathomimetic decongestants can potentially lead to serious adverse reactions, including hypertensive crisis 4

High-Risk Populations Requiring Caution

Pseudoephedrine should be used with extreme caution or avoided in patients with specific comorbidities. 1, 3

• Cardiovascular disease patients: Those with uncontrolled hypertension, arrhythmias, angina pectoris, or cerebrovascular disease are at increased risk 1, 3, 4
• Elderly patients and young children: Higher risk of adverse effects including agitated psychosis, ataxia, hallucinations, and even death in infants and young children 1
• Patients with hyperthyroidism, glaucoma, or bladder neck obstruction should avoid this combination 1

Common Pitfalls to Avoid

• Hypertensive patients: While controlled hypertensive patients can generally use pseudoephedrine safely, blood pressure monitoring is recommended due to interindividual variation 2
• Duration of use: Limit pseudoephedrine use to the shortest duration possible to minimize cardiovascular risks 4
• Anticholinergic burden: Be aware that chlorpheniramine adds to total anticholinergic burden, particularly problematic in elderly patients 1