I gave 2 tsp of zyrtec 1mg/ml syrup to my 4,5 year old son. then i realised that this is 4 times of the recommended dose for 2-6 years old children. shall i worry about it or what do you recommend me to do? thank you in advance?

Call you local poison control center telephone number. NOW. They know best thing to do in Turkey.

I'm not sure how long ago you posted this. Always good idea to call poison control, but sometimes I see children with severe allergies who need that dose and do fine. Probably no need to worry.

Not to worry , your son probably had a good long sleep. I am glad that you caught your mistake but, do be careful next time as other medications may do more harm to the body. Always double check yourself as other OTC medications indeed have a higher dose in children. Not everyone is the same.Always read the dosing chart carefully and follow as recommended.