Loss of appetite: possible causes and diagnosis

The clinician will usually ask when appetite changed, whether you feel full quickly, and whether there is nausea, pain, diarrhoea, fever, cough, low mood or swallowing difficulty. They may review medicines, alcohol use, dental problems, diet and changes in strength or weight. Gastritis, peptic ulcer, gastroenteritis, influenza, COVID-19 and depression are examples of conditions that can affect appetite; these symptoms do not identify one diagnosis by themselves.

The examination and history determine whether tests are useful. The aim is to find a treatable cause and check for effects such as dehydration or inadequate nutrition.

Keep a short record of meals, drinks, symptoms, bowel changes, fever and medicines. Note whether smells, pain or nausea stop you eating. Continue fluids and choose small nourishing portions while waiting for advice. Bring a list of supplements and regular medicines, including recent changes.

Arrange an appointment for persistent or unexplained appetite loss, repeated early fullness, ongoing vomiting, pain, weakness or unplanned weight change. Seek urgent care for severe abdominal pain, vomiting blood, black stools, fainting, confusion, inability to drink or breathing difficulty. The urgency depends on these red flags, not on appetite loss alone.

Which causes fit my symptom pattern? Do I need an examination or tests? Could a medicine, dental issue or mood change be involved? What changes should prompt earlier review?