When should you see a doctor about unexplained weight loss?

Weight can fall when appetite changes, food becomes difficult to swallow, the body absorbs less nutrition, or illness alters energy use. Dental problems, digestive disease, thyroid conditions, mood changes, medicines, infection, and cancer can all be considered. Weight loss may accompany bowel, lung, oesophageal, pancreatic, blood, or lymphatic cancers, but it is not specific to cancer and cannot establish a diagnosis on its own.

Write down when the change began, your usual eating pattern, appetite, swallowing, bowel habits, pain, cough, fever, sleep, mood, and medicines. If possible, use the same scale and record readings without obsessively checking. Tell the clinician about diet changes, dental issues, recent illness, and any difficulty preparing or accessing food. They may assess nutrition and choose tests based on your history and examination.

Seek urgent help if weight loss is accompanied by inability to swallow fluids, repeated vomiting, severe dehydration, coughing blood, black or bloody stools, chest pain, fainting, confusion, or sudden marked weakness. Contact your cancer team promptly if treatment is making it difficult to eat or drink.

Ask what might explain the change, whether nutrition support could help, which tests are suitable, and what symptoms should lead to an earlier review.