Concomitant use with sympathomimetic agents such as decongestants and tricyclic antidepressants may occasionally cause a rise in blood pressure.

Guaifenesin

If urine is collected within 24 hours of a dose of guaifenesin a metabolite of guaifenesin may cause a colour interference with laboratory determinations of urinary 5-hydroxyindoleacetic acid (5-HIAA) and vanillylmandelic acid (VMA).

4.6 Pregnancy and lactation
The safety of this product during pregnancy and lactation has not been established, but in view of a possible association of foetal abnormalities with first trimester exposure to pseudoephedrine, the use of the product during pregnancy should be avoided. The amounts of pseudoephedrine and guaifenesin secreted into breast milk are considered too small to be harmful.

4.7 Effects on ability to drive and use machines
No adverse effects known.

4.8 Undesirable effects
Guaifenesin

The following side effects may be associated with the use of guafenesin:

Gastrointestinal disorders: Nausea, vomiting, gastrointestinal discomfort.

Immune system disorders: Hypersensitivity reactions.

Pseudoephedrine

Cardiovascular disorders: Tachycardia, palpitations, other cardiac dysrhythmias.

Gastrointestinal disorders: Nausea and/or vomiting.

General disorders and administration site conditions: Irritability.

Immune system disorders: Hypersensitivity reactions, including cross-sensitivity that may occur with other sympathomimetics.

Nervous system disorders: Headache, tremor, anxiety, restlessness, excitability, dizziness, insomnia, hallucinations (particularly in children) and paranoid delusions.

Psychiatric disorders: Confusion and sleep disturbance.

Renal and urinary disorders: Difficulty in micturition including urinary retention.

Skin and subcutaneous tissue disorders: Skin reactions including rash.

Vascular disorders: Hypertension.

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 at www.mhra.gov.uk/yellowcard.
4.9 Overdose
Symptoms of overdosage include irritability, restlessness, palpitations, hypertension, difficulty in micturition, nausea, vomiting, thirst and convulsions. In severe overdosage gastric lavage and aspiration should be performed. Symptomatic and supportive measures should be undertaken particularly with regard to the cardiovascular and respiratory systems. Convulsions should be controlled with intravenous diazepam. Chlorpromazine may be used to control marked excitement and hallucinations. Severe hypertension may need to be treated with an alpha-adrenoreceptor blocking drug, such as phentolamine. A beta blocker may be required to control cardiac arrhythmias.

5. Pharmacological properties
5.1 Pharmacodynamic properties
Pseudoephedrine is a sympathomimetic agent with direct and indirect effects on adrenergic receptors. It has alpha and beta adrenergic activity and some stimulant effect on the central nervous system. The sympathomimetic effect of pseudoephedrine produces vasoconstriction which in turn relieves nasal conges