**Question:** The commonest side effect of cisplatinum in a patient using it for esophageal carcinoma is

A. Nausea and vomiting
B. Neurological symptoms
C. Hair loss
D. Skin rash

**Core Concept:**
Cisplatinum is a chemotherapeutic agent used for the treatment of various cancers, including esophageal carcinoma. It belongs to a class of drugs known as platinum-based compounds, which exert their cytotoxic effects by forming DNA adducts, leading to cell cycle arrest, DNA fragmentation, and ultimately cell death.

**Why the Correct Answer is Right:**
The commonest side effect of cisplatinum is **Nausea and vomiting**. These symptoms result from the drug's action on the gastrointestinal tract and central nervous system. Cisplatinum can cause direct damage to the mucosal lining of the gastrointestinal tract, leading to inflammation, ulceration, and increased secretion of gastrointestinal hormones, such as gastrin and motilin, which stimulate the gastrointestinal tract and lead to nausea and vomiting.

**Why Each Wrong Option is Incorrect:**

A. **Neurological symptoms**: Although cisplatinum can cause neurological side effects, they are generally less common than gastrointestinal side effects.

B. **Hair loss (alopecia)**: Although cisplatinum can cause hair loss, it is not the most common side effect.

C. **Skin rash**: While it is possible to have a rash as a side effect, nausea and vomiting are more frequently observed.

**Clinical Pearls:**
1. Understanding the side effects of cisplatinum is crucial for managing patients receiving this drug.
2. Monitoring patients for common side effects such as nausea and vomiting can help to adjust the treatment plan and provide appropriate symptomatic management.
3. Always consult the patient's history and physical examination findings to differentiate drug-induced side effects from other potential causes of symptoms.