Feeling tired for a few days is common. Persistent, worsening or unexplained fatigue can have many physical, psychological, lifestyle and medication-related causes, so the most useful first step is a clinical conversation that guides any tests appropriately.
A private GP can review the pattern of fatigue, sleep, mood, diet, medicines, menstrual history, infections and other symptoms before recommending investigations.
Blood tests can identify some treatable contributors, but normal results are also useful: they help focus the next clinical question rather than automatically proving that nothing is wrong.
Written & reviewed by
Victoria Medical Clinical Team
GMC-registered physicians and specialist consultants
Common causes of persistent tiredness
Fatigue is a symptom, not a diagnosis. It may be linked to poor sleep, stress, low mood, anaemia, thyroid disease, diabetes, nutritional deficiency, infection, medication effects or other medical conditions.
| Pattern or accompanying symptom | Possible clinical direction | Typical next step |
|---|---|---|
| Breathlessness, paleness or heavy periods | Anaemia or iron deficiency | GP assessment and targeted blood tests |
| Weight change, heat/cold intolerance | Thyroid or metabolic cause | Clinical review with thyroid/metabolic testing where indicated |
| Thirst and frequent urination | Diabetes or other metabolic issue | Prompt GP review and glucose/HbA1c assessment |
| Snoring or unrefreshing sleep | Sleep disorder | Sleep history and appropriate referral pathway |
When blood tests may be useful
Depending on your history, a clinician may consider a full blood count, ferritin, thyroid function, glucose or HbA1c, kidney and liver markers, vitamin B12, folate or vitamin D. The right panel depends on your symptoms and risk factors.
When to seek urgent help
Urgent assessment is important if fatigue comes with chest pain, severe breathlessness, fainting, new confusion, vomiting blood, black stools, rapidly worsening weakness or thoughts of self-harm.
Call 999 for a medical emergency. Do not wait for a routine blood-test appointment if you have severe or rapidly worsening symptoms.
Frequently Asked Questions
References
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