How to reduce side effects of birth control pill(levonorgestrel 1.5 mg) ? should we get worry about those side effects? in case of side effects what medications should be used?

See doctor: here is a brief list of major and minor side effects. https://www.drugs.com/sfx/levonorgestrel-side-effects.html For specifics to your situation one would need to know what side effects. Usually there is an alternative medication that can be considered depending on the side effect. Best approach is a consult with a doctor licensed in your area to give specific advice.

Assuming that you: are female -although this lists you as being a 23 year old male. You didn't tell us which side effects you were experiencing. The best option is to let your prescribing provider know. This current medication/ dosage may not be a optimum choice for you if you are experiencing significant or numerous side effects.