Hi thanks for contacting practo for health query. Your question is interesting,how to improve the immune system.I am Dr.Shanmugavadivu a senior physician answering your query You have half of the answer exercise.More than medicines a balanced nutritious diet should help. You look into the diet of yours 60% of your energy should come from carbohydrates 20to 25 %from protein and10 to15% from fat.Include fruits and vegetables at least two portions 100gms and 200gms each time respectively.See to that you include greens 4 times a week and also take probiotics like curd regularly.Exercise wise go for floor aerobics and yoga. Suriya namaskar is a great way of boosting immune system. Medicine to boost up immune system you can take zinc , micronutrients and vitamins Hope this helps.