Contafever N Syrup may rarely cause drowsiness, dizziness, blurred vision, and a delay in motor reactions, which may severely affect the patient’s ability to drive or operate machinery. If you experience these symptoms, do not engage in any activities that require alertness or quick reactions until you feel you can do those activities safely. It is worth noting that the elderly (over 65 years) are more susceptible to these neurological effects. It should also be noted that alcohol/wine may exacerbate these symptoms, and taking Contafever N with other antihistamines increases drowsiness and dizziness.