Idiopathic intracranial hypertension (IIH) and multiple sclerosis (MS) are rare neurological disorders that largely affect females within the reproductive age group. The clinical pictures of both diseases can overlap, which therefore places great importance on accurately studying and reporting their concurrence. Therein, we report a case of IIH presenting and progressing simultaneously with MS. This young, previously healthy female presented with the primary complaint of a severe right-sided headache associated with blurred vision and a finding of papilledema. The initial investigations including a lumbar puncture (LP) that revealed high opening pressure (more than 25 mm H2O) with normal cerebrospinal fluid (CSF) analysis led to an impression of idiopathic intracranial hypertension, and she was treated accordingly with acetazolamide and scheduled for regular follow-ups with both neurology and neuro-ophthalmology. However, about two months after the initial presentation, she complained of unusual headaches, and a neuro-ophthalmology clinical evaluation revealed complete right homonymous hemianopia, suggesting a lesion in the left temporo-parietal occipital region. The patient was thus admitted as a case of cerebral edema following an urgent brain magnetic resonance imaging (MRI). After obtaining thorough imaging and workup, the patient was given steroids and markedly improved, favoring a diagnosis of tumefactive MS with IIH.