Anxiety is defined as a feeling of worry, nervousness, or unease. Blood pressure is the force exerted by circulating blood against the artery walls. The body’s typical reaction to anxiety is a temporary increase in this pressure, which is an expected part of the stress response. However, a distinct physiological response exists where intense anxiety can cause blood pressure to fall rapidly. This less common, paradoxical reaction can lead to confusing and alarming symptoms.
How Anxiety Typically Impacts Blood Pressure
The body’s standard reaction to sudden anxiety or perceived danger is the activation of the “fight or flight” response. This immediate reaction is orchestrated by the Sympathetic Nervous System (SNS). Activation of the SNS triggers the rapid release of stress hormones, notably adrenaline and cortisol, into the bloodstream.
These hormones prepare the body for immediate action by causing the heart to beat faster and increasing the heart rate. Simultaneously, the hormones cause vasoconstriction, the narrowing of small arteries throughout the body. The combination of increased heart output and narrowed blood vessels results in a temporary spike in blood pressure.
This short-term elevation explains why anxiety, such as during a medical check-up, is often associated with a high blood pressure reading. Frequent activation of the SNS in individuals with chronic anxiety may also contribute to a sustained increase in systemic vascular resistance over time.
The Mechanisms That Cause Blood Pressure to Drop
While the sympathetic system typically raises blood pressure, an intense emotional trigger can cause the opposite reaction, known as the vasovagal reflex. This response is a sudden, paradoxical switch in the autonomic nervous system’s control, where the Parasympathetic Nervous System (PNS) abruptly takes over instead of the SNS. The PNS acts via the vagus nerve, which runs from the brainstem and directly influences heart function.
When the vasovagal reflex is triggered, the vagus nerve becomes overstimulated, leading to two major physical changes. It causes bradycardia, a sudden slowing of the heart rate, and rapid, widespread vasodilation, especially in the lower extremities. These two actions—a slower heart rate and dilated blood vessels—cause a sharp drop in blood pressure, or hypotension.
Because blood pressure falls quickly, the brain does not receive sufficient blood flow, leading to lightheadedness or fainting (syncope). This response is often triggered by specific phobias, such as the sight of blood or needles, or by extreme emotional duress.
Anxiety can also lead to hyperventilation during a panic attack, which contributes to lightheadedness. Rapid, shallow breathing reduces carbon dioxide in the blood, causing blood vessels in the brain to constrict. This further reduces blood flow, mimicking the effects of low blood pressure even without severe syncope.
Recognizing Symptoms and When to Seek Medical Help
When anxiety causes blood pressure to drop, the physical manifestations can be sudden and intense. Common signs of anxiety-induced hypotension include:
- Lightheadedness or dizziness
- Nausea
- A cold or clammy sweat
- Paleness of the skin
- Vision changes, such as blurred vision or “tunnel vision”
Vision changes can precede fainting due to the temporary lack of oxygen to the brain. These symptoms typically resolve quickly once the person lies down, which helps restore blood flow to the head.
A severe drop in pressure can signal a more serious underlying issue, requiring immediate medical attention. Seek urgent care if low blood pressure is accompanied by confusion, chest pain, difficulty breathing, or a weak yet rapid pulse.
Repeated episodes of fainting, or any loss of consciousness not quickly followed by a full return to awareness, should prompt a medical evaluation to rule out cardiac or neurological causes.