BackgroundBath-related headache (BRH) is a rare primary headache disorder with only about 50 cases reported from 2000 to 2017 and none since. It is an abrupt onset excruciating headache occurring predominantly in middle-aged Asian women, most commonly following exposure to hot water. This is the first report in a Sri Lankan woman.Case presentationA 60-year-old Sri Lankan woman presented with an abrupt onset, severe throbbing holocephalic headache immediately following a hot-water shower. The headache was not associated with photo- or phonophobia, nausea, or vomiting, and she did not report a past history of migraine. However, she had experienced a similar headache 2 years previously precipitated by a hot-water shower. Her neurological examination, blood investigations, and magnetic resonance imaging of brain and intracranial vessels were normal. She was treated with opioid and nonsteroidal antiinflammatory drug analgesics, but the headache resolved only after treatment with nimodipine. The headache did not recur during a follow-up of 2 years since she avoided hot-water showers.ConclusionsBath-related headache is a thunderclap primary headache disorder with a benign prognosis, but its recognition requires awareness to differentiate it from subarachnoid hemorrhage. It warrants inclusion in the International Classification of Headache Disorders.