Hi, Thanks for posting in HCM. I understand your concern. Decolgen contains Phenylephrine, Chlorphenamine Maleate and Paracetamol. It is a decongestant medication, which is used for the relief of clogged nose, runny nose, postnasal drip, itchy and watery eyes, sneezing, headache and body aches. It is not known to cause hallucinations as such. However, its ingredient Phenylephrine may cause restlessness, anxiety, nervousness, weakness, dizziness, pain or discomfort in the chest, tremors and respiratory distress. If the side effects persist or becomes bothersome, kindly seek medical attention promptly. Hope the information provided would be helpful. All the best.