Background Neurological symptoms following head trauma are common; however, the cause may not always be obvious. In the absence of open wounds, fractures, or surgical interventions, infectious causes may not be considered, especially viral infections such as Herpes simplex, and investigations may not be targeted to investigate this possibility. Case A 39-year-old male presented with a severe headache, reduced consciousness, and confusion. Two days earlier, he had been discharged from the hospital, where he had been treated for traumatic brain injury with subarachnoid hemorrhage following a road traffic accident. Herpes simplex virus type 2 (HSV-2) was detected in the cerebrospinal fluid, confirming the diagnosis of viral meningoencephalitis. He was treated with oral aciclovir for two weeks and achieved full neurological recovery. Conclusions This case highlights the risk of viral reactivation following trauma, particularly head injuries. Central nervous system infections, including viral infections, should be considered in cases of delayed deterioration following trauma, likely presenting with worsening headache, drowsiness and reduced cognitive state. The optimal treatment of herpes simplex virus (HSV) encephalitis may be challenging in resource-limited settings.