In poisoning or erroneous acceptance of medications the most rapid and first aid measure is to try to vomit immediately as this is effected easiest when you insert your index and middle finger as deeper as possible into your throat. Secondly - organize yourself a transport to a hospital or emergency center to make you gastrointestinal lavage. Thirdly - if you cannot get to the emergency you can still help yourself by using activated carbon as shown in its leaflet.
A book about the 50 most common diseases, how to treat them and how to avoid generally being sick.