What should you know about loss of thirst and appetite?

Appetite and thirst can fall during infections such as influenza, COVID-19, gastroenteritis, or Hepatitis A. Nausea, abdominal discomfort, gastritis, peptic ulcer disease, and other digestive problems may make eating unattractive. Depression can affect interest in food and the usual awareness of hunger or thirst. Some medicines, pain, constipation, dental problems, and changes in taste or smell can have a similar effect. Less thirst does not prove that the body needs less fluid; illness, heat, vomiting, diarrhoea, or fever can increase fluid needs without creating a strong thirst signal.

Take frequent small sips rather than waiting to feel thirsty, especially during fever, vomiting, or diarrhoea. Choose fluids you tolerate and eat small, nourishing portions such as soup, yoghurt, eggs, or soft foods. If nausea is present, bland foods and a calm eating environment may help. Keep a note of urination, vomiting, diarrhoea, new medicines, and how much you are managing. Older adults, children, and people with chronic illness can become unwell sooner; ask a clinician or pharmacist for individual guidance, including whether oral rehydration is suitable.

Seek urgent help for confusion, fainting, severe weakness, trouble breathing, blood in vomit or stool, severe abdominal pain, or inability to keep fluids down. Prompt advice is needed for very little or dark urine, a dry mouth with worsening dizziness, yellowing of the skin or eyes, or rapid deterioration. Arrange a medical review when reduced eating or drinking persists, weight is falling, swallowing is difficult, or mood symptoms are affecting daily life.

Could an infection, digestive condition, medicine, dental issue, or low mood explain these changes? How can I monitor hydration, and which symptoms should trigger urgent help? Do I need an examination or blood tests?