Dimetapp Paediatric Elixir is contra-indicated in patients sensitive to any of the ingredients and in infants or neonates. It should not be given to patients whose sensitivity to small doses of sympathomimetic substances is manifested by sleeplessness, dizziness, light headaches, weakness, tremulousness or cardiac arrhythmia.
In fact, worrying (or anxiety) can stimulate the release of epinephrine into your system, whereby it will bind with your beta-adrenergic receptors in your liver, causing your blood vessels to constrict and your blood pressure to rise, along with your heart rate (pulse).
Beta-blockers are drugs that bind to beta-adrenoceptors and thereby block the binding of norepinephrine and epinephrine to these receptors. This inhibits normal sympathetic effects that act through these receptors. Therefore, beta-blockers are sympatholytic drugs.