Is it bad to take all medicines(different types of medicine) together?does it reduce the effectiveness of the medicine or not?and does it cause overdose or not?

Please be more specific in your repost. What medicines? What directions were you given by the physician writing these prescriptions, and what does it say on the label? Different medications can be taken at different times of the day, but your prescribing physician is best prepared to guide you.

Meds should be taken as prescribed and a good resource will be the pharmacist dispensing them. Some can be taken at the same time with others, while others have to be taken separately at a different time for absorption related reasons mostly.