What cancer-related fatigue is, and why it is not "being tired"
Cancer-related fatigue is a physical, mental and emotional exhaustion that is out of proportion to the effort made and does not improve with rest. Between 70 % and 90 % of people on chemotherapy report it, and in some it persists for months or years after finishing. It is caused by the tumour itself (inflammation), by the treatments and by everything around them: anaemia, poor sleep, pain, anxiety, less activity, poorer nutrition.
It is a real, measurable symptom, not a lack of willpower. And it is largely treatable, but only if it is talked about: many people do not mention it because they assume it is inevitable or do not want to "complain".
First: rule out what can be fixed
Ask your team to check these causes, because each has its own treatment:
- Anaemia: very common with chemotherapy and with bleeding from the tumour. It is measured in blood tests (haemoglobin, iron, ferritin, B12, folate). Intravenous iron or, in specific cases, a transfusion make a big difference to energy.
- Thyroid: immunotherapy and some drugs disturb it; a TSH test detects it.
- Poorly controlled pain: it is exhausting. It needs treating.
- Low mood or anxiety: fatigue and depression feed each other. Asking about it is not an insult; treating it improves energy.
- Sleep: insomnia, sleep apnoea, long naps that disrupt the night, steroids taken in the afternoon.
- Medicines: anti-sickness drugs, opioids, antihistamines, some antidepressants and muscle relaxants cause drowsiness; sometimes the timing or dose can be adjusted.
- Malnutrition and muscle loss, dehydration, abnormal sodium, potassium or calcium, infections.
What works best: moving
It sounds contradictory, but the measure with the strongest evidence for reducing fatigue is regular physical exercise, during and after treatment. Dozens of clinical trials confirm it; resting more, by contrast, worsens the cycle (less muscle → more fatigue → less activity).
- Start by walking: 10-15 minutes a day, building up gradually to 30 minutes on most days.
- Add strength work twice a week (sit-to-stand from a chair, resistance bands, small weights, climbing stairs). Muscle is your "battery".
- Adapt the intensity to the day: less in the first week of the cycle, more in the second. What matters is not stopping altogether.
- If you can, ask about supervised oncology exercise programmes (many hospitals, patient associations and the AECC, the Spanish cancer association, offer them, including online).
- With bone metastases, low platelets or fever, check first what you can do.
Managing your energy
- Prioritise: each day, one or two things that matter; delegate or drop the rest. Asking for help is part of treatment.
- Plan demanding tasks for your good hours (note for a week when you have most energy).
- Short naps (20-30 minutes, before 3 pm), not whole afternoons on the sofa: they wreck night-time sleep.
- A sleep routine: same time every night, daylight in the morning, screens away, bed only for sleeping.
- Eat regularly and drink enough: mild dehydration feels like tiredness.
Psychological support and other measures with evidence
- Cognitive behavioural therapy and mindfulness programmes reduce fatigue moderately and are well documented. Psycho-oncology is free in many Spanish hospitals and through the AECC.
- Adapted yoga and tai chi have positive results in several studies.
- American ginseng showed some benefit in one trial, but it interacts with drugs: do not take it without checking.
- Stimulant drugs (methylphenidate, modafinil): inconsistent results; reserved for specific cases, for example in advanced disease. Low-dose corticosteroids can help for a few days in advanced stages.
What has shown nothing
Multivitamins "for energy" (if there is no deficiency), energy drinks, detox diets, coenzyme Q10 or L-carnitine supplements. They cost money and sometimes interfere with treatment.
Returning to work
Fatigue is the most common reason people struggle to return to work. In Spain you can request a phased return or adjustments to your post; talk to your GP, your employer's occupational health service and, if needed, the hospital social worker. Do not measure yourself against who you were before treatment: energy takes months to recover, and that is normal.
What to ask at your appointment
- Do I have anaemia, iron deficiency or a thyroid problem in my latest blood tests?
- Could any of my medicines be adding to the tiredness?
- Is there an oncology exercise or rehabilitation programme at the hospital or nearby?
- Can I see a psycho-oncologist?
- How long does this fatigue usually last in my situation, and what sign would suggest something else is going on?