Hello,
He should be taken to the hospital immediately for immediate care.
Dettol (Chlorxylenol) is an antiseptic which when comes into contact with living bacteria, it kills them, however when it comes into contact with living tissue it will cause irritation.
Since the gentleman appears to have swallowed about 500 ml of this antiseptic, it could cause irritation to the lining of the oral cavity, food pipe, or the stomach resulting in ulcerations. It may result in
severe vomiting,
abdominal pain, coughing due to aspiration, urinary disturbances, and altered levels of consciousness.
So, in my opinion, you should inform his brother to take him immediately to the emergency room of the nearest hospital. Meanwhile, that gentleman may be given
cold milk for the symptomatic relief.
Hope I have answered your query. Let me know if I can assist you further.
Regards,
Dr. Mohammed Taher Ali