The combination of dizziness and profuse sweating usually indicates some type of physical or mental distress. The list of possible causes is extensive, ranging in severity from nearly fainting due to stong emotions, such as fear or grief, to a life-threatening heart or lung problem.
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If you've ever nearly fainted at the sight of blood or a needle, or in response to tragic news, you've experienced situational presyncope — the medical term for nearly fainting. Also known as a vasovagal reaction, situational presyncope occurs when a circumstance provokes an exaggerated or abnormal nervous system response.
This reaction stimulates sweating as well as a drop in blood pressure and heart rate, which in turn causes reduced blood flow to the brain and dizziness. A vasovagal reaction is the leading cause of presyncope and outright fainting. Situational presyncope triggers include:
- Emotional distress
- An upsetting sight
- Severe pain
- Exposure to extreme heat
- Standing for long periods
Cardiovascular disorders — those involving the heart and circulatory system — are a leading consideration in people who experience dizziness and profuse sweating. In most cases, dizziness occurs due to decreased outflow of blood from the heart leading to reduced delivery of blood to the brain.
In response, certain types of nerves are activated in an attempt to stimulate the heart's output. These nerves, called sympathetic neurons, also trigger profuse sweating, or diaphoresis. Some of the more common cardiovascular disorders that can cause dizziness and diaphoresis include:
- Heart attack
- Heart failure
- Abnormal heart rhythms
- Narrowing of the mitral, aortic or pulmonary heart valve
- Pulmonary embolism — a blood clot one or more lung arteries
- Aortic dissection — a tear in the lining of the aorta, the largest artery of the body
Dizziness and profuse sweating can signal a metabolic derangement. Critically low blood sugar, or hypoglycemia, is one example. This condition primary affects people with diabetes, usually due to an imbalance between food intake and blood-sugar-lowering medications.
Hypoglycemia can also occur with several rare disorders, such as certain tumors and genetic enzyme defects. The brain normally relies exclusively on blood sugar to generate energy.
Hypoglycemia deprives the brain of this essential nutrient, leading to disruption of normal brain functions and symptoms such as dizziness, moodiness, shakiness and difficulty concentrating. Low blood sugar also stimulates the sympathetic nerves, which triggers increased glucose production and excessive sweating.
Low blood oxygen, or hypoxemia, can also trigger dizziness and profuse sweating, as can a low level of carbon dioxide. These metabolic abnormalities most commonly occur with severe heart or lung disease. Low blood carbon dioxide can also occur with hyperventilation.
Dizziness with hypoxemia occurs because lack of oxygen disrupts normal brain function. A low carbon dioxide level triggers this symptom by reducing blood flow to the brain. Both abnormalities stimulate the sympathetic nerves, which leads to sweating.
The conditions and disorders discussed represent many of the most common causes of dizziness and profuse sweating, but there are a number of other possible culprits. Some of these include:
- Anxiety, panic and depressive disorders
- Inner ear disorders
- Moderate to severe allergic reactions
Warnings and Precautions
Situational presyncope does not pose a threat to your health and symptoms typically clear within a few minutes if you lie down. However, other causes of dizziness and profuse sweating are potentially serious and might be life threatening.
Contact your doctor as soon as possible if you experience these symptoms. Seek immediate medical care if these symptoms are accompanied by any warning signs and symptoms, including:
- Wheezing, throat tightness, shortness of breath or difficulty breathing
- Chest pain or pressure
- Pounding, racing or irregular heartbeat
- Confusion, agitation or other mental changes
- Severe or worsening abdominal pain
- Swelling of the lips, face or tongue
Reviewed and revised by: Tina M. St. John, M.D.