Can i become allergic to sertraline after 4 months? i just increased my dose 4 days ago.

Unlikely: Allergies develop but it is unlikely to become allergic after taking the medication for 4 months. Increasing your dose could lead to new side effects. Check with your doctor or pharmacist.

Sertraline: It depends on what you mean by "allergic". Sometimes an increase in any dose will have some temporary adjustment. You may be having an intolerance though to the higher dose? It depends on the severity of the complaints