Hello,
Hair thinning one of the signs of hair loss, so it's better to start taking care from the beginning, consult a dermatologist and under his prescription follow the treatments and medications.
you are having one side more thinning of hair loss, so kindly inform your doctor regarding.
Hair loss related treatments like PRP, derma roller, laser light therapy, micro needling, etc is good for controlling your hair loss.
Along with treatments topical and oral medications also suggest to be used.
Medications like minoxidil and finasteride can help you to support controlling hair loss, But if you wanted to have good hair density on the side area then hair transplant will be the best option.
I hope it will be helpful for you.