Infection and loss of appetite: what to know

During an infection, the immune response can cause tiredness, fever, body aches, and a temporary drop in hunger. A blocked nose or changes in smell and taste can also make familiar food seem unappealing. Some infections irritate the stomach or bowel, causing nausea, vomiting, diarrhoea, cramps, or early fullness. COVID-19 and influenza can present with reduced appetite, while gastroenteritis and hepatitis A may combine poor appetite with digestive symptoms.

Loss of appetite is a symptom, not a diagnosis. Its significance depends on what else is happening, how long it lasts, and whether you can drink and pass urine normally. Medicines taken during an illness can sometimes worsen nausea or alter taste, so record any recent prescription or non-prescription products and mention them to a clinician.

Take frequent small sips of water or an oral rehydration drink, especially if fever, vomiting, or diarrhoea is present. Eat small portions when you can rather than waiting for a normal appetite. Soft, plain foods such as soup, rice, yoghurt, toast, or bananas may be easier to tolerate; choose nourishing foods with protein when they appeal to you. Avoid forcing a large meal, and limit alcohol while you are unwell.

Rest, monitor your temperature if you feel feverish, and notice whether symptoms are improving. If you have diabetes, are pregnant, are older, or have a long-term condition, seek tailored advice earlier because reduced intake can affect medicines and blood glucose. Do not stop a prescribed medicine without checking with the prescriber or pharmacist.

Get urgent medical help if you cannot keep fluids down, faint or become confused, have severe or worsening abdominal pain, vomit blood, pass black stools, or have trouble breathing. Seek prompt advice if you are passing very little urine, have a very dry mouth, or feel markedly weak, as these can indicate dehydration.

Arrange a medical review if appetite does not begin to return as the infection settles, if weight is falling without trying, or if poor appetite keeps recurring. Persistent appetite loss can also occur with conditions such as gastritis, peptic ulcer, depression, or pancreatic cancer, so ongoing symptoms deserve assessment rather than self-treatment.

Ask which infection best fits your other symptoms, whether you need testing, and which drinks or foods are suitable for you. You can also ask whether a medicine may be affecting your appetite, how to manage vomiting or diarrhoea, and which warning signs should prompt urgent care. Bring a list of medicines and note what you have managed to drink and eat.