Waterpipe (hookah) smoking is popular; in Dutch surveys, 26% of the respondents have smoked a waterpipe at least once. However, waterpipe smoking is not without risk. We present a series of carbon monoxide (CO) poisonings after waterpipe smoking and discuss the etiology and treatment of CO intoxication after waterpipe smoking.We present three patients who presented with syncopial episodes and a variety of other neurological and circulatory symptoms after smoking a waterpipe. All patients had significantly elevated carboxyhaemoglobin levels (26%, 19% and 26%). Patients were treated with oxygen, following Dutch guidelines; one patient was admitted for eight hours of oxygen therapy. The other two patients were observed shortly, diverging from the guidelines because symptoms passed and the carboxyhaemoglobin normalised.Reviewing combustion chemistry, the formation of CO is a logical consequence of using burning coals as a heat source. This is due to CO2 reduction with carbon. This chemical process has not previously been related to waterpipe smoking. Dutch guidelines advise eight hours of oxygen therapy. The research this guideline is based on, justifies therapy directed at symptom relief and carboxyhaemoglobin normalisation. This strategy may prevent unnecessary hospital admissions and exposure to high-dose oxygen.We described three cases of CO intoxication after waterpipe smoking and argue why this may not be an incidental finding. Greater awareness of this risk is urgently needed. We conclude that the literature does not firmly support a fixed treatment duration.