Most common side effect of long term heavy dose of carbamazepine is:

 # Most common side effect of long term heavy dose of carbamazepine is:

A. Aplastic Anemia

B. Fluid retention

C. Renal toxicity

D. Gingival hyperplasia

The correct answer is: A. Aplastic Anemia.

Explanation:

Carbamazepine is an antiepileptic drug with several potential side effects. The most common long-term serious side effect associated with heavy doses of carbamazepine is hematological toxicity, including aplastic anemia and agranulocytosis, though these are rare.

A. Aplastic Anemia: Correct. Long-term use of carbamazepine can suppress bone marrow, leading to aplastic anemia.

B. Fluid Retention: While carbamazepine can cause hyponatremia due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH), this is not the most common severe long-term side effect.

C. Renal Toxicity: Carbamazepine is not primarily known for causing renal toxicity.

D. Gingival Hyperplasia: This is more commonly associated with drugs like phenytoin, not carbamazepine.