I have a health insurance policy that also reimburses outpatient (OPD) charges and medicines. I want to know if it will also cover homeopathy or ayurveda treatment. If not, can a special rider be taken for these covers?

There are a few options available – example: Star Health covers homeopathy in post operative treatment (after returning from hospital) HDFC Ergo covers 20% of Sum Insured provided you are treated in approved Ayurveda hospital.

No you cannot take it as a special rider.