Low blood pressure may also be attributed to heat stroke which can be indicated by absence of perspiration, light headedness and dark colored urine.Other medications can produce hypotension by different mechanisms. Chronic use of alpha blockers or beta blockers can lead to hypotension. Beta blockers can cause hypotension both by slowing the heart rate and by decreasing the pumping ability of the heart muscle.Decreased cardiac output despite normal blood volume, due to severe congestive heart failure, large myocardial infarction, heart valve problems, or extremely low heart rate (bradycardia), often produces hypotension and can rapidly progress to cardiogenic shock. Arrhythmias often result in hypotension by this mechanism.Excessive vasodilation, or insufficient constriction of the blood vessels (mostly arterioles), causes hypotension. This can be due to decreased sympathetic nervous system output or to increased parasympathetic activity occurring as a consequence of injury to the brain or spinal cord. Dysautonomia, an intrinsic abnormality in autonomic system functioning, can also lead to hypotension. Excessive vasodilation can also result from sepsis, acidosis, or medications, such as nitrate preparations, calcium channel blockers, or AT1 receptor antagonists (Angiotensin II acts on AT1 receptors). Many anesthetic agents and techniques, including spinal anesthesia and most inhalational agents, produce significant vasodilation.Lower blood pressure is a side effect of certain herbal medicines, which can also interact with several medications. An example is the theobromine in Theobroma cacao, which lowers blood pressure through its actions as both a vasodilator and a diuretic, and has been used to treat high blood pressure.
There are also syndromes that can cause hypotension in patients including orthostatic hypotension, vasovagal syncope, and other rarer conditions.For many people, excessively low blood pressure can cause dizziness and fainting or indicate serious heart, endocrine or neurological disorders.For some people who exercise and are in top physical condition, low blood pressure could be normal. A single session of exercise can induce hypotension and water-based exercise can induce a hypotensive response.Treatment of hypotension may include the use of intravenous fluids or vasopressors. When using vasopressors, trying to achieve a mean arterial pressure (MAP) of greater than 70 mmHg does not appear to result in better outcomes than trying to achieve a MAP of greater than 65 mmHg in adults. Signs and symptoms
The primary symptoms of hypotension are lightheadedness or dizziness.If the blood pressure is sufficiently low, fainting (syncope) may occur.Low blood pressure is sometimes associated with certain symptoms, many of which are related to causes rather than effects of hypotension:

Causes
Low blood pressure can be caused by low blood volume, hormonal changes, widening of blood vessels, medicine side effects, severe dehydration, anemia, vitamin B12 deficiency, anaphylaxis, heart problems or endocrine problems.Reduced blood volume, hypovolemia, is the most common cause of hypotension. This can result from hemorrhage; insufficient fluid intake, as in starvation; or excessive fluid losses from diarrhea or vomiting. Hypovolemia can be induced by excessive use of diuretics.