**Question:** A 23-year-old individual who believes in megavitamins therapy develops severe headache, and fundoscopy reveals papilloedema. The likely cause for this problem is -

A. Vitamin A overdose
B. Vitamin C overdose
C. Vitamin E overdose
D. Vitamin B complex overdose

**Core Concept:**

Megavitamins therapy refers to excessive intake of vitamin supplements, often in the belief that it will enhance overall health and wellbeing. Overdosing on vitamins can lead to various complications, including neurological manifestations due to disruption of homeostasis and toxic effects on the central nervous system.

**Why the Correct Answer is Right:**

Among the given options, Vitamin D overdose is the most likely cause for the severe headache and papilloedema in this scenario. Vitamin D is essential for calcium homeostasis and bone health. However, excessive intake can lead to hypercalcemia, which results in neurological symptoms like headache and papilloedema due to increased intracranial pressure.

**Why Each Wrong Option is Incorrect:**

1. Vitamin A overdose: Papilloedema is associated with hypovitaminosis A, not hypervitaminosis A.
2. Vitamin C overdose: Although excessive Vitamin C intake can cause gastrointestinal symptoms like nausea and vomiting, papilloedema is less commonly associated with this vitamin.
3. Vitamin E overdose: Similar to Vitamin A, papilloedema is less commonly associated with Vitamin E overdose.
4. Vitamin B complex overdose: While some B vitamins may cause gastrointestinal symptoms, the combination of severe headache and papilloedema is more likely due to Vitamin D overdose.

**Clinical Pearl:**

This case emphasizes the importance of maintaining a balanced intake of vitamins and minerals. Vitamin overdose can lead to severe neurological symptoms, emphasizing the need for cautious vitamin supplementation. Always consult with a healthcare professional before initiating vitamin supplementation, especially in high doses.