What causes persistent fatigue?

Persistent fatigue can result from poor sleep, stress, medicines, infection, anaemia, hormonal problems, or an underlying medical condition. Cancer and blood disorders can also cause tiredness through anaemia, inflammation, changes in metabolism, or the effort needed to manage illness. Fatigue on its own does not identify the cause.

Fatigue is different from ordinary sleepiness: rest may not restore your energy, and everyday tasks may feel unusually demanding. A clinician may ask when it began, whether it is worsening, how you sleep, what medicines you take, and whether you have weight change, fever, breathlessness, pain, bleeding, or swollen glands. Blood tests can look for anaemia, infection, thyroid problems, and other clues. Persistent fatigue may occur with conditions such as leukaemia, lymphoma, multiple myeloma, myelodysplastic syndromes, myeloproliferative neoplasms, or Waldenstrom Macroglobulinaemia, but these symptoms also occur for many non-cancer reasons.

Arrange a medical assessment if fatigue continues, affects work or self-care, or has no clear explanation. Keep a short record of sleep, activity, meals, medicines, associated symptoms, and changes over time. Gentle activity within your limits, regular meals, fluids, and a consistent sleep routine may help while you wait. Do not start iron or other supplements without advice, because treatment depends on the cause. Blood Transfusion Support may be considered when a clinician finds a specific blood-related reason; Palliative Care can help manage fatigue and other symptoms alongside treatment for serious illness.

Seek urgent medical help for fatigue with severe breathlessness, chest pain, fainting, new confusion, heavy bleeding, a high fever, or sudden weakness. Contact your care team promptly if you have known cancer and develop rapidly worsening exhaustion, new bruising, repeated infections, or difficulty staying awake.

What causes should we check first? Which blood tests or medicine reviews are appropriate? Could anaemia, thyroid problems, sleep disruption, or infection explain this pattern? What symptoms should prompt urgent contact?