Blood Pressure Changes During Illness: Patterns by Etiology

Acute illness alters blood pressure via hemodynamic, inflammatory, and neurohormonal pathways:

Viral Infections (Cold, Flu, COVID-19)

Often unchanged or mildly ↓ due to vasodilation, dehydration, reduced intake. Fever may ↑ HR but not necessarily BP.

Bacterial Infections (Pneumonia, UTI, Sepsis)

• Early sepsis: Vasodilation → hypotension (shock).
• Compensated: Catecholamine surge → transient hypertension.
• Renal involvement: Volume overload → hypertension.

Chronic Diseases (CKD, Diabetes)

Baseline hypertension common; acute illness exacerbates via volume, RAAS activation, medication nonadherence.

Dehydrating Illnesses (Gastroenteritis, DKA)

Hypovolemia → ↓ BP, orthostatic hypotension, tachycardia.

Medication Effects

NSAIDs (↑ BP via prostaglandin inhibition), decongestants (↑ BP), missed antihypertensives.

Clinical Action

• Trend BP serially; don't overreact to single readings.
• Correct volume status first.
• Hold antihypertensives if SBP <100 or symptomatic hypotension.
• Restart/up-titrate once stable.

Persistent abnormality post-recovery warrants outpatient follow-up.