Upset stomach, light-headedness and fatigue: what to know

Vomiting, diarrhoea, fever, or simply eating and drinking less can leave you dehydrated. Dehydration may cause thirst, a dry mouth, darker urine, weakness, and light-headedness. Fatigue can also accompany a viral illness, anaemia, coeliac disease, or a longer-term condition such as chronic kidney disease. Burnout, alcohol use, and sleep disruption can add tiredness, but they do not explain every combination of stomach symptoms and dizziness.

Light-headedness means feeling faint or unsteady; spinning suggests vertigo and needs a different assessment. Note whether symptoms began suddenly, follow standing, or occur after meals, and record vomiting, diarrhoea, urine changes, fever, and medicines.

Rest, rise slowly, and take frequent small sips of water or an oral rehydration drink if you have lost fluid. Choose easy-to-tolerate foods when able, and avoid alcohol while unwell. Do not drive or climb if you feel faint. Arrange a medical review if fatigue continues, symptoms recur, you cannot maintain fluids, or the pattern is unexplained; assessment may include vital signs and blood tests.

Seek urgent help for fainting, confusion, severe weakness, chest pain, difficulty breathing, new one-sided weakness, severe abdominal pain, blood in vomit or stool, very little urine, or repeated vomiting that prevents drinking. Fever with marked deterioration also warrants prompt assessment.

Ask whether dehydration, anaemia, infection, medication effects, or another condition could account for the pattern; whether blood tests are needed; and how much fluid is suitable for you if you have kidney or heart problems.