Really weak immune system.., what can i do?

Immune system : The immune system requires a constant and sufficient supply of protein to maintain optimum function. When humans are starved their immune systems weaken. Therefore maintain adequate protein.

Specify: You need to specify what kinds of illnesses you are having since a weak immune system can mean many things. If you are not producing enough antibodies, then antibiotic prophylaxis or immunoglobulin replacement may be considered. If you are just asking about what improves the immune system, then regular exercise and a healthy diet may help. Vitamin d3 supplement may also be needed.