Hello. Thanks for asking from HCM. I can understand your concern. Hitting head with another person is usually not very serious as impact force is not very much. But you are having feeling of drowsiness and weakness, so it needs proper evaluation. You have not mentioned the time of injury. If it is already 3 or more days old and you are conscious, oriented with symptom free interval in between, it is a mild injury. With time, you will recover. For your complaints, other causes should be ruled out like fever, chronic fatigue, generalised weakness etc. If injury is fresh and there was never a symptom free interval or you are having complaints despite taking painkillers, you should consult ER as soon as possible. Meanwhile, you can follow these tips : Closely watch for alarming signs like vomiting, loss of consciousness, decreasing consciousness, onset of new focal deficit, persistently increasing headache. Any of these signs suggest dangerous head injury. : Keep your head higher than chest : In case of vomiting, turn head to side : Take bed rest for 2-3 days and avoid strenuous activities : Keep yourself hydrated and well nourished, as sometimes poor nutrition and fluid intake can cause weakness If no relief in symptoms or alarming signs appear, consult ER. The doctor may advise CT scan of head to rule out skull bone fracture or clot. Thanks. Hope it will help you. take care.