Background: Headache disorders are among the most common neurological conditions in the world and, in some individuals, are often associated with dietary factors. Mustard and its derivatives are condiments that contain bioactive compounds such as allyl isothiocyanate and glucosinolate derivatives, which affect vascular function and neurochemical signalling. Despite its presence in everyday diets, the potential role of mustard as a trigger for headache is understudied. Therefore, this study aims to explore whether mustard—in its various forms, including seeds, pastes, and sauces—may act as a dietary factor associated with headache occurrence.