Why Do I Keep Getting Low-Grade Fever, Headaches, and Fatigue Even When Doctors Say Nothing's Wrong?

This is the story of Mr. B, an office worker. He said that although he had fully recovered from a severe sore throat he had suffered three weeks prior, his overall condition had not improved, and these symptoms recurred daily. He had finished the antibiotics prescribed by his doctor, but the low-grade fever, headache, daytime fatigue, and post-meal bloating persisted.

If all these symptoms were simply post-infectious sequelae, they should naturally resolve after a certain period. This would be even more true if the virus had been suppressed with antibiotics and rest. However, Mr. B's body is still struggling to recover. This is a counter-indicator his body is sending.

So, what is the true cause of this complex set of symptoms that appear without a specific diagnosis?

We can view this issue as an 'emergency alarm from the autonomic nervous system due to the depletion of the body's resources (Qi and Yin).'

Recent convergence studies in Korean traditional medicine and modern medicine interpret this phenomenon as a complex imbalance in the body's systems. While battling an infectious disease, our body expends immense energy and vital fluids (Yin, 陰) to fight the virus. Like a city in ruins after a war, the virus may have receded, but the body remains in a depleted state.

In Korean traditional medicine, this is interpreted through the lens of 'Yin Deficiency with Internal Heat (陰虛內熱).' Yin (陰) refers to the body's material resources such as vital fluids, blood, and water. When these are depleted, the Yang (heat) relatively becomes agitated, leading to symptoms like low-grade fever and headache. This is similar to an engine overheating because there isn't enough coolant to dissipate the heat.

From the perspective of modern medicine, this is related to autonomic nervous system imbalance. The autonomic nervous system regulates all bodily functions through the balance of the sympathetic nervous system (excitation) and the parasympathetic nervous system (rest). At night, the parasympathetic nervous system should activate for rest, but when the body is not recovering and remains in a depleted state, this system does not function properly. Consequently, during the day, there is such a lack of energy that activity is impossible, and at night, even though the body should be resting, emergency signals like low-grade fever, headaches, and sleep disturbances continuously ring out. This precisely matches the temporal pattern he complains of: 'morning fatigue' and 'evening low-grade fever.'

This imbalance also affects the digestive system. When the autonomic nervous system is disturbed, gastrointestinal motility decreases, which can lead to symptoms like Mr. B's complaint of 'bloating even after drinking only water.' The body's imbalance travels throughout the system, sending signals in various ways.