There are many possible causes of chills, the most common being fever. Therefore, patients are advised to monitor their body temperature and consider a fever if their axillary temperature exceeds 37.3°C.
Other causes such as acute upper respiratory tract infection, influenza, gastrointestinal tract infection, urinary tract infection, etc. may also cause fever, so routine blood tests, C-reactive protein, viral tests and chest CT are needed for clarification.
If you don’t have a fever but have chills, you need to have further tests such as thyroid function, blood sugar, blood count, kidney function and vascular ultrasound to rule out hypoglycaemia, hypothyroidism, anaemia and peripheral vascular disease, which can also cause chills.