BACKGROUND Lumbar puncture (LP) is a key diagnostic tool for various pathologies but can lead to complications, including post-LP headache (PLPH). Post-LP cerebral venous thrombosis (CVT) is a rare but serious complication with an annual incidence of 1.16 to 2.02 per 100 000 population. It is more common in females, with a ratio of 3: 1 compared to males. Exogenous estrogen use is an antecedent risk factor for thrombosis. CASE REPORT A 29-year-old woman, gravida 0 with a 3-year history of using etonogestrel/ethinyl estradiol vaginal ring (NuvaRing) for contraception, presented to the emergency room with 2 days of fever, altered mental status, and body aches. Her initial imaging showed no abnormalities, including head computed tomography (CT), CT angiography, and head magnetic resonance imaging (MRI). An LP was negative. A persistent headache prompted placement of an epidural blood patch 6 days later, and a subsequent MRI revealed a thrombus in the superior sagittal sinus and a cortical infarct. Use of the NuvaRing was discontinued, and the patient was treated with anticoagulants. Follow-up imaging showed chronic venothrombotic changes but no new thrombosis. The diagnosis of the condition leading to the original admission and workup was never determined. CONCLUSIONS Post-LP cerebral venous thrombosis can be life-threatening if not promptly diagnosed and treated. Persistent headaches, new neurological deficits, and unexplained symptoms after LP should prompt investigation for cerebral venous thrombosis. Early diagnosis with MRI with magnetic resonance venography (MRV) and appropriate anticoagulation therapy are crucial for managing this complication. The combination of a NuvaRing and LP temporally associated with a CVT is unreported and likely increased her risk of thrombosis.