Chlorpheniramine blood level analysis is used to measure the concentration of chlorpheniramine in the blood, which is an antihistamine medication used to treat allergy symptoms such as sneezing, runny nose, and itching. This test is used to determine the drug level in the body to ensure appropriate dosing and to avoid toxicity or adverse effects resulting from drug accumulation. It is recommended in cases of high or repeated dosing of chlorpheniramine or when side effects are suspected.