Radiotherapy is an important tool in cancer care. Yet for many people, a common challenge during (and sometimes after) this treatment is overwhelming fatigue. This is not just “being tired” — it’s a kind of exhaustion that seeps into many parts of life, making daily tasks feel heavier.
In this post, we’ll look at why radiotherapy can lead to fatigue, how people often describe and experience it, and practical strategies to cope. While we can’t offer medical claims, we’ll also gently mention how complementary supports (such as nutritional or herbal formulations) may play a role in your overall routine. Always check with your oncology or care team before trying anything new.
What is fatigue in the context of cancer and radiotherapy?
Fatigue in cancer (often called “cancer-related fatigue”) is different from normal tiredness. With everyday fatigue, rest and sleep tend to restore energy. But in cancer-related fatigue, even extended rest might not fully help.
From NHS guidance:
“Many people having radiotherapy feel tired (fatigued) a lot of the time or become tired very easily from doing everyday activities. This usually starts during treatment and can continue for several weeks or months after treatment finishes.”
Because everyone is different (different cancer types, treatment regimens, and baseline health), fatigue presents uniquely in each person.
Why does radiotherapy often lead to fatigue?
There is no single cause; fatigue during radiotherapy is usually multifactorial. Below are common contributing elements:
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Damage to healthy (non-cancer) cells
Radiotherapy aims to kill or damage cancer cells, but inevitably some healthy tissues around the treatment area get affected. The body then uses energy to repair or clear those damaged cells, which may divert resources from other functions. -
Inflammation and shifts in biochemistry
Radiation can trigger a cascade of inflammatory signals and stress in the body. These changes may influence fatigue, hormones, and the way cells generate energy. -
Anaemia or lowered blood counts
In some treatments, radiotherapy can affect blood cells or bone marrow function, leading to anaemia, which reduces oxygen delivery to tissues, amplifying tiredness. -
Treatment burden and logistics
Frequent hospital visits, travel, waiting times, stress, and disruptions in sleep or routine—all these add up. Over time, this cumulative burden can drain energy. -
Other symptoms that worsen fatigue
Radiotherapy may also cause side effects such as nausea, appetite loss, digestive issues, and sleep disturbances. These symptoms can worsen fatigue indirectly. -
Emotional and psychological strain
Anxiety, mood changes, stress, and fears about prognosis all consume energy. Emotional fatigue can compound physical fatigue. -
Reduced physical activity
Because one feels tired or unwell, people often reduce their movement. But reduced activity can weaken muscles, reduce circulation, and create a vicious cycle that worsens fatigue.
Over the weeks of a radiotherapy course, these effects often build up. Many patients report that fatigue gradually worsens as treatment continues.
You may also like: what is the difference between cancer-related fatigue and normal fatigue
What does the NHS say?
From the NHS “Side effects of radiotherapy” page:
“Many people having radiotherapy feel tired (fatigued) a lot of the time or become tired very easily from doing everyday activities. This usually starts during treatment and can continue for several weeks or months after treatment finishes.”
That aligns with patient experiences: fatigue is a known and common side effect of radiotherapy, not an accident or “unexpected”. It’s something to plan for and manage proactively.
How do people describe it?
Common experiences include:
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Feeling as if your “battery drains fast”
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Loss of interest in activities you used to enjoy
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Needing long naps or rest periods just to get through the day
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Difficulty concentrating or “brain fog”
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Irritability or mood swings
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Greater sensitivity to even light physical tasks
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Sometimes waking up unrefreshed
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Taking longer to recover after exertion
These aren’t just “side effects” — they shape quality of life, mood, relationships, and independence.
Coping strategies: Supportive routines
Since we can’t offer medical claims, the advice here is supportive, general, and meant to complement—but never replace—your medical team’s guidance. Always check with your oncologist, nurse, or care team before trying new routines or supplements.
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Communicate openly with your care team
Let them know how fatigue is affecting your life. Sometimes they can adjust scheduling or supportive medications or refer you to services. -
Plan and pace your activities
Break tasks into smaller steps, alternate activity with rest, and use a fatigue diary to spot when you have more energy. -
Gentle movement
Paradoxically, being too inactive can worsen fatigue. But the key is gentle and appropriate: short walks, light stretching, or movement at home. Always check with your clinical team first. -
Good sleep hygiene
Keep consistent sleep and wake times, create a calm bedtime routine, and keep naps short so they don’t disturb night sleep. -
Nutrition and hydration
Fuelling your body well helps with energy. Try small, frequent meals, keep hydrated, and include protein- and nutrient-rich foods. -
Emotional support
Stress and fatigue are linked. Relaxation, mindfulness, or talking with others can help. -
Accept help
Whether it’s shopping, cooking, or chores — accept help where you can. It conserves energy for what matters most.
Complementary supports: a gentle note on HBK
If you are exploring non-drug, supportive approaches as part of a holistic routine, some people consider nutrient or herbal blends (with their care team’s approval).
For instance, our HBK Formula natural support for cancer-related weakness is a blend of 17 natural ingredients — including mushrooms, turmeric and herbs — designed as a gentle daily wellness powder. While it is not a treatment for cancer or fatigue, some people like to use such products as part of their general wellness routine, alongside nutrition, rest, and movement.
Always check with your doctor or nurse before adding anything new during treatment.
FAQs
Q: Will radiotherapy-related fatigue always go away after treatment?
Not always immediately. Many people find fatigue gradually improves in the weeks or months after radiotherapy ends, but for some it lingers.
Q: Could exercise make it worse?
It depends on the intensity. Light, appropriate activity can help, but over-exertion may backfire. Always go gently.
Q: Can supplements fix fatigue?
There’s no universal “fix”. Some people explore supportive nutrition or herbal blends, but these should only be considered with medical guidance.
Q: What signs mean I should speak to my doctor?
If fatigue suddenly worsens or comes with dizziness, breathlessness, chest pain, or confusion — contact your care team.
Q: Is fatigue a sign that cancer is getting worse?
Not necessarily. Fatigue is a recognised side effect of radiotherapy and other treatments. But it’s always wise to discuss changes with your specialist.
Final thoughts
Radiotherapy fatigue is real, and it’s more than just feeling “a bit tired”. It touches on every part of life, but with planning, pacing, and supportive routines, many people find ways to navigate it. Always lean on your care team, make adjustments day by day, and consider complementary supports if they feel right for you.
