caffeine + paracetamol + phenylephrine hydrochloride: clinical use

Prescribing considerations

• Confirm that the patient has both pain or fever symptoms and nasal congestion.
• Review non-prescription products for duplicate paracetamol, caffeine or sympathomimetic ingredients.
• Assess cardiovascular, hepatic, renal, endocrine, ophthalmic and urological comorbidity.
• Consider caffeine exposure and susceptibility to insomnia, anxiety, palpitations or gastrointestinal irritation.
• Use particular caution with severe illness, sepsis, malnutrition, chronic alcohol excess or glutathione depletion.

Contraindications and cautions

• Hypersensitivity to an active ingredient or excipient
• Hypertension, severe coronary heart disease or another significant cardiovascular disorder
• Hyperthyroidism
• Current MAOI treatment or use within the preceding two weeks
• Concurrent sympathomimetic decongestant use
• Prostatic enlargement
• The selected Lemsip product additionally contraindicates phaeochromocytoma, closed-angle glaucoma and diabetes mellitus; check the exact product

Monitoring

• Blood pressure and pulse when cardiovascular risk or interacting treatment is relevant
• Insomnia, agitation, anxiety, tremor or excessive caffeine exposure
• Urinary difficulty or retention
• Liver-risk factors and duplicate paracetamol exposure
• Acid–base status with unexplained high-anion-gap metabolic acidosis, particularly with flucloxacillin or glutathione depletion

Clinical pharmacology

Paracetamol has central analgesic and antipyretic effects. Caffeine is an adenosine-receptor antagonist and central stimulant. Phenylephrine is predominantly an alpha-1 adrenergic agonist that reduces nasal mucosal swelling through vasoconstriction; oral bioavailability is limited by first-pass metabolism.

Formulation and product differences

• Both selected products are red and yellow hard gelatin capsules intended to be swallowed whole.
• Excipient lists are similar but not identical: the selected Lemsip formulation includes shellac, while the selected Benylin formulation lists maize starch.
• Both selected formulations are described as essentially sodium-free.
• Contraindications and precautions differ between product licences, so check the exact product.

Capsule

Route: Oral

Strengths: 300 mg + 25 mg + 5 mg