An Unusual Overdose + Listener Mail

Tetrahydrozoline ingestion causes a clonidine-like toxidrome with bradycardia and hypotension, and severe cases can follow seemingly benign eye-drop exposures. Also, abnormal uterine bleeding on oral contraceptives often reflects inadequate estrogen dosing or a nonhormonal cause, while compartment syndrome becomes limb-threatening within hours, not days.

Tetrahydrozoline Eye-Drop Overdose

• Imidazoline alpha-2 agonism: Tetrahydrozoline is an imidazoline derivative with central alpha-2 effects, so systemic overdose looks much more like clonidine toxicity than a local ophthalmic exposure.
• Bradycardia hypotension pattern: The hallmark toxidrome is bradycardia with hypotension from central alpha-adrenergic activation, and even complete AV block has been reported after Visine ingestion.
• Adult self-harm exposure: Most cases are accidental pediatric ingestions, but adults may present after intentional overdose, making a bottle of eye drops an easy miss in the suicidal patient.
• Supportive care first: Treatment is mainly supportive with IV fluids, vasopressors for persistent shock, and atropine when clinically important bradycardia is driving the picture.
• Observation and disposition: Patients generally improve with monitoring and supportive care rather than antidotal therapy. We get into the practical ED course in the episode.

Abnormal Bleeding While On OCPs

• Estrogen dose mismatch: Breakthrough or intermenstrual bleeding while on oral contraceptives is often managed by increasing the estrogen content to a 30-35 mcg pill.
• Short high-dose rescue: For heavier bleeding between cycles, a temporary higher-intensity oral contraceptive regimen can stabilize the endometrium before transition to a new pack.
• Tranexamic acid role: If cycles stay regular but the menses themselves are especially heavy, adding tranexamic acid to ongoing OCP therapy may be a useful adjunct.
• Antiemetic co-prescribing: Escalated estrogen dosing commonly causes nausea, so antiemetics should be prescribed alongside the short rescue course rather than added later.
• Structural cause warning: Do not assume the bleeding is purely hormonal; fibroid, polyp, malignancy, and bleeding disorder remain key alternatives, and the workup pathway matters. We walk through the practical cautions in the chapter.

Chest Pain Protocols And Safety Nets

• Second troponin timing: A low-risk HEART score should not erase symptom timing; chest pain present for under 6 hours is a common reason to build in an automatic second troponin.
• Worrisome story override: An abnormal ECG plus a concerning history may justify serial troponins even when a streamlined single-troponin pathway would otherwise seem acceptable.
• SCAD miss reduction: SCAD is the kind of diagnosis that reinforces protocol discipline, because an initially negative troponin may declare itself only after repeat testing.
• Protocolization advantage: Standardized chest pain algorithms reduce bedside improvisation and help teams apply the same safety checks reliably across shifts and clinicians.

References:

1. Schmidt AH, et al; METRC. Predicting Acute Compartment Syndrome (PACS): The Role of Continuous Monitoring. J Orthop Trauma. 2017 Apr;31 Suppl 1:S40-S47. PMID: 28323801.

2. Afify O, Suleiman AM, Mohamed HG, Saaed O. Complete atrioventricular block due to ingestion of Visine eye drops. BMJ Case Rep. 2021 May 12;14(5):e241905. doi: 10.1136/bcr-2021-241905. PMID: 33980559; PMCID: PMC8118060.