Differential Diagnosis for Vomiting of Unknown Cause

Single Most Likely Diagnosis

• Gastroenteritis: This is often the most common cause of vomiting, typically resulting from a viral or bacterial infection. The justification for this being the single most likely diagnosis is its high prevalence and the fact that it can affect anyone, regardless of age or health status.

Other Likely Diagnoses

• Food Poisoning: Similar to gastroenteritis, food poisoning is a common cause of vomiting, usually occurring after the consumption of contaminated food or drinks.
• Viral Gastrointestinal Infections: Infections such as norovirus or rotavirus can cause severe vomiting, especially in children and immunocompromised individuals.
• Motion Sickness: For individuals who have recently traveled by car, boat, plane, or other means, motion sickness is a plausible cause of vomiting.
• Pregnancy: Morning sickness is a well-known symptom of early pregnancy, which can include vomiting.

Do Not Miss Diagnoses

• Appendicitis: Although less common, appendicitis can present with vomiting, especially if the appendix is located near the stomach or intestine, causing irritation.
• Intestinal Obstruction: This is a serious condition where the intestine is blocked, which can lead to severe vomiting and requires immediate medical attention.
• Pancreatitis: Inflammation of the pancreas can cause severe abdominal pain and vomiting.
• Kidney Stones: While primarily known for causing severe pain, kidney stones can also induce vomiting.
• Meningitis: In severe cases, especially in children, meningitis can present with vomiting, among other symptoms like fever and headache.

Rare Diagnoses

• Brain Tumors: Certain brain tumors, especially those that increase intracranial pressure, can cause vomiting.
• Cyclic Vomiting Syndrome: A rare condition characterized by recurring episodes of severe vomiting with no apparent cause.
• Addison's Disease: A rare endocrine disorder where the adrenal glands do not produce enough cortisol and aldosterone, which can lead to vomiting among other symptoms.
• Porphyrias: A group of rare genetic disorders that can cause a variety of symptoms, including vomiting.

Each of these diagnoses has a unique set of accompanying symptoms and risk factors that can help guide further investigation and diagnosis. It's crucial to consider the patient's medical history, recent activities, and other symptoms when evaluating the cause of vomiting.