Summer Fatigue or Something More Serious? Doctor Reveals When to Seek Help
Prof. Dr. Darko Katalinić warns that exhaustion lasting longer than four weeks could signal serious health issues, from iron deficiency to thyroid disease.
Prof. Dr. Darko Katalinić warns that exhaustion lasting longer than four weeks could signal serious health issues, from iron deficiency to thyroid disease.
Summer is at its peak, days are long, and many are eagerly awaiting their annual vacation. Yet instead of a surge of energy, an increasing number of people feel the opposite-chronic exhaustion, drowsiness, and lack of concentration. While it's easy to blame the heat, Prof. Dr. Darko Katalinić, MD, from Croatia Polyclinic, emphasizes that prolonged fatigue is not harmless and may indicate more serious deficiencies in the body.
The feeling of summer lethargy is not imagined. According to Prof. Katalinić, it is a complex reaction of the body to a heatwave. To cool down, the body dilates blood vessels, increases sweating, and accelerates the heart rate. "During a heatwave, the body is constantly working, even when a person is at rest," the doctor explains. This continuous effort consumes extra energy, resulting in a feeling of heaviness and lack of strength.
A key factor is also dehydration. Many make the mistake of waiting for the feeling of thirst, which, as Prof. Katalinić warns, is already a delayed signal. "Thirst is not an early indicator of fluid deficiency; it appears only when dehydration has already advanced." Even mild fluid loss can cause a drop in concentration, headaches, and fatigue. The problem is further exacerbated by the loss of electrolytes such as sodium, potassium, and magnesium through sweating. "In people who sweat heavily, their deficiency can cause weakness, muscle cramps, dizziness, and a feeling that the body lacks energy," the doctor explains.
Heat directly affects sleep quality. To fall asleep, body temperature must drop, which is difficult during muggy nights. "Sleep becomes shallower, awakenings are more frequent, and the proportion of deep sleep decreases," notes Prof. Katalinić. As a result, you can spend eight hours in bed and wake up completely exhausted. Additionally, summer lifestyle often brings sudden changes-from later bedtimes to more intense physical activity that the body is not accustomed to. "Although physical activity is extremely beneficial for health, a sudden increase in load without adequate rest can lead to cumulative fatigue," the doctor warns.
Typical summer fatigue usually resolves after rest and hydration. However, Prof. Katalinić emphasizes that there is a clear red line when exhaustion is no longer harmless. "Such fatigue is not just a feeling of sleepiness but a deep sense of exhaustion that makes it difficult to perform daily activities," he explains. It is crucial to pay attention to accompanying symptoms such as unexplained weight loss, elevated temperature, night sweats, or difficulty breathing, which could indicate heart, lung, or even diabetes.
The doctor particularly stresses the importance of monitoring the duration of symptoms. "Fatigue lasting longer than four weeks without a clear reason, progressively worsening, or significantly impacting daily life requires medical evaluation," says Prof. Katalinić.
One of the most common causes of prolonged exhaustion is iron deficiency. What many don't know is that fatigue can occur even before anemia develops. "It's important to know that fatigue can occur even before hemoglobin becomes low, when only iron stores, i.e., ferritin levels, are reduced," the doctor points out. Along with iron, vitamin B12 and folic acid are also crucial for energy levels. Prof. Katalinić warns of serious consequences if neglected: "Prolonged untreated vitamin B12 deficiency can cause permanent damage to the nervous system."
The first impulse for chronic fatigue is often reaching for supplements, but the doctor advises caution. "Modern medicine is based on evidence that clearly shows supplements are not universally beneficial for everyone," says Prof. Katalinić. Self-initiated intake can mask the true cause of illness and, in some cases, be directly harmful. "Excessive iron intake can cause liver, pancreas, and heart damage, while excess zinc can lead to copper deficiency, anemia, and weakened immune function," the doctor notes. Instead of guessing, targeted laboratory diagnostics are recommended.
One way to check nutritional status is the IMUNO package from Croatia Polyclinic, which includes tests for vitamin D, B12, folic acid, ferritin, magnesium, calcium, and a complete blood count. "Combining assessments of vitamin D, vitamin B12, folic acid, ferritin, blood count, magnesium, and calcium can reveal common but often overlooked disorders such as iron deficiency, vitamin deficiencies, or changes in the blood count," explains Prof. Katalinić. "Laboratory tests allow treatment to be tailored to the individual's actual needs," the doctor concludes, adding that results must always be interpreted in the context of age, symptoms, and the patient's overall health. Until August 31, 2026, the package is available at a promotional price of 98 euros, a 51 percent discount.
