What to do if i have drunk a whole bottle of piriton?

Go to emergency room: As opposed to sitting and typing a perfect stranger online. Antihistamines in very high doses can have serious adverse consequences, including some life-threatening ones. Why did you do this? If it was with the plan of hurting/killing yourself, you need urgent and immediate psychiatric help. If it was to get "high, " you need help with chemical dependency. Seek a mental health professional now.