A 33-year-old woman employed as a warehouse associate without significant past medical history presented to the ED with bilateral lower extremity weakness that had been progressive for one month. The patient reported that symptoms initially began as a “pins and needles” sensation in her feet that slowly progressed to a “heavy” sensation and difficulty walking. She denied recent trauma, illness, or pain and disclosed she regularly huffed 20–30 “balloons” of NO two to three times a month. On physical exam, she had normal vital signs, cranial nerve function, and rectal tone. She had decreased bilateral lower extremity strength with decreased sensation to pinprick, vibration, and pain to the mid-abdomen with full sensation and strength preserved in her upper extremities. In addition, she had a positive Lhermitte’s sign and Romberg test with diminished, 1+ patellar and Achilles reflexes with 2+ brachioradialis, and biceps and triceps reflexes bilaterally. The patient was admitted to the neurology ward. Laboratory results obtained after admissions were notable for a decreased vitamin B12 level with an elevated methylmalonic acid level without macrocytosis, normal levels of intrinsic factor without antibodies, and unremarkable cerebrospinal fluid studies with normal inflammatory and infectious markers. Folate and copper levels were also found to be normal. Radiographic findings including contrasted magnetic resonance imaging brain and spine were normal. Electromyography studies did not suggest demyelination; however, they were abnormal and suggestive of myeloneuropathy in the setting of vitamin B12 deficiency from NO use. The patient was administered high-dose vitamin B12 injections (1,000 micrograms daily) with significant clinical improvement. The patient was discharged home on day three of hospitalization with a walker and outpatient physical therapy. At eight-week neurology follow-up, the patient was able to ambulate independently with 5/5 strength in bilateral hip flexors with negative Romberg. The patient had full resolution of symptoms one year after initial onset. She maintained sobriety from NO, and her vitamin B12 and methylmalonic acid levels have remained normal.