Systemic lupus erythematosus may present with fever, and it is a challenge to attribute fever to a particular cause. Very rarely it can be due to hyperthyroidism. Thyroid storm is a medical emergency causing unrelenting pyrexia. Here we report a case of a young female who first presented as fever of unknown origin (FUO), was subsequently diagnosed as neuropsychiatric lupus, and in whom the cause of unrelenting high fever, which did not respond to adequate immunosuppression to quell disease activity, was documented to be thyroid storm after excluding all other causes such as infection and malignancy. To our knowledge, this is the first case of this kind reported in literature, although cases of thyrotoxicosis preceding or following the diagnosis of lupus is known. Her fever resolved after starting antithyroid drugs and beta blockers.