Question

Adverse effects of Phenytoin include the following except:

• A. Lymphadenopathy.
• B. Ataxia.
• C. Hypercalcemia.
• D. Hirsutism.

Hint:

Phenytoin speeds vitamin D breakdown, causing hypocalcemia, not hypercalcemia.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
We need the one option that is NOT a recognised side effect of phenytoin, an old and widely used antiepileptic drug.

Step 2: Key Concept:
Phenytoin has a well known list of side effects affecting the gums, skin, nervous system, blood, and bone. It also interferes with vitamin D metabolism in the liver, which affects calcium handling in the body.

Step 3: Detailed Explanation:
Phenytoin can cause a pseudolymphoma like reaction with generalised lymphadenopathy, sometimes confused with true lymphoma, so lymphadenopathy is a recognised effect.
Ataxia, along with nystagmus and slurred speech, is a classic sign of phenytoin toxicity affecting the cerebellum, so it is a well known adverse effect.
Phenytoin induces liver enzymes that break down vitamin D faster, this lowers active vitamin D, which in turn lowers calcium absorption from the gut. Long term use is linked to hypocalcemia and osteomalacia, not hypercalcemia. So hypercalcemia is not something phenytoin causes, if anything it pushes calcium levels down.
Hirsutism (excess hair growth), along with gum overgrowth (gingival hyperplasia) and coarsening of facial features, is a well documented cosmetic side effect of long term phenytoin use.

Step 4: Why the other options are wrong:
Lymphadenopathy, ataxia, and hirsutism are all genuine, textbook adverse effects of phenytoin, so they are correctly linked to the drug and are not the exception.

Step 5: Final Answer:
Phenytoin does not cause hypercalcemia, it tends to cause hypocalcemia instead.
\[ \boxed{\text{Hypercalcemia}} \]