Within 30 minutes of intake, caffeine typically causes:

• A. No change
• B. A permanent increase in SBP only
• C. A decrease in DBP
• D. A transient rise in SBP and DBP by several mmHg depending on tolerance

Answer: (D)

Caffeine acts as a stimulant that acutely shifts cardiovascular tone. When you take it, it blocks adenosine receptors and increases sympathetic activity, causing vasoconstriction and a higher heart rate. Because of this, blood pressure rises briefly. Within about 30 minutes you typically see a temporary rise in both systolic and diastolic pressures by a few mmHg, and how large that rise is depends on tolerance from regular caffeine use—regular consumers usually experience a smaller increase. The effect is transient and fades as caffeine is metabolized, not a permanent change. It isn’t zero change or a decrease in pressure, and it isn’t limited to just one blood pressure value.