A pharmacist has revealed when tiredness crosses the line from ordinary to a "red flag". According to Niamh McMillan, Superdrug's pharmacy superintendent, ongoing exhaustion could be the body's way of "screaming" for attention - and in certain circumstances blood tests might uncover an underlying condition such as nutrient deficiencies or thyroid imbalance.

"Feeling a little more tired during winter is normal," Niamh explained. "But when exhaustion becomes constant and affects concentration, mood or daily functioning, it can be a red flag that something isn't quite right internally."

Fatigue and hidden deficiencies

"Low energy levels are commonly linked to deficiencies in nutrients such as iron, vitamin B12 and vitamin D, all of which play a crucial role in energy production, oxygen transport and overall wellbeing," said Niamh.

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"These deficiencies are particularly common during winter when diets change and sunlight exposure drops.

"Because symptoms often creep in gradually, people can go months feeling drained without realising there's an underlying cause. Blood testing allows us to look beyond surface symptoms and understand what the body is actually missing."

In some instances, persistent fatigue may suggest a thyroid imbalance. "The thyroid gland regulates metabolism and energy levels, so when it's underactive, people may experience persistent fatigue, brain fog, weight changes and sensitivity to cold," Niamh explained.

"These symptoms are often mistaken for stress or seasonal burnout, which means thyroid issues can go undetected for longer than they should.

"Blood testing is one of the most effective ways to identify whether the thyroid is functioning properly and whether further medical advice is needed."

Spotting the warning signs – from within

Niamh continued: "For anyone struggling with unexplained tiredness, Superdrug Online Doctor offers a Thyroid Screen Blood Test for £69 that can identify how well your thyroid is functioning.

"The process is discreet, convenient and provides clear results that help people take the next step - whether that's lifestyle changes, supplements or speaking to a healthcare professional. For those looking to support their energy levels, Superdrug's own-brand vitamins and supplements offer an affordable option for all purses."

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