Lorazepam-Induced Orthostatic Hypotension and Secondary Headache in a Low Blood Pressure Phenotype

A 30-year-old man with a lifelong low but stable blood pressure (BP) (typically 90-95/50-55 mmHg) developed dose-related orthostatic symptoms and evening headaches after the initiation of nightly lorazepam. Classic orthostatic hypotension (OH) thresholds were not consistently met; however, standing repeatedly reproduced symptoms with concurrent heart rate (HR) increases, a pattern more consistent with orthostatic intolerance (OI) time-locked to benzodiazepine (BZD) exposure. Symptoms were reliably worse on 2 mg nights and attenuated on 1 mg or off-nights (dechallenge/re-challenge). Co-exposure to a tricyclic antidepressant (TCA) and a first-generation antihistamine (AH) increased anticholinergic burden (ACB), aligning with nocturnal nasal dryness and ocular surface complaints. Baseline evaluation (complete blood count (CBC), comprehensive metabolic panel (CMP), thyroid function, hemoglobin A1c (HbA1c), electrocardiogram (ECG)) showed no secondary causes. Urinalysis (UA) on high-symptom days demonstrated higher specific gravity with intermittent ketonuria and hyaline casts (per low-power field (LPF)), suggesting relative dehydration as a modulator. The case highlights BZD-related autonomic dampening in a constitutional low BP phenotype and supports practical safeguards: individualized dosing, orthostatic BP/HR monitoring with symptom logging, reduction of total anticholinergic load, hydration/salt strategies, and cognitive behavioral therapy for insomnia (CBT-I)-first insomnia care.