The Mayo Clinic explains that some doctors consider a blood pressure as being low if the top number is lower than 90 or the bottom number is lower than 60. Furthermore, if a person has a healthy top number, but a low bottom number, he still has low blood pressure. This reading may appear as 115/60. Women typically have lower blood pressure than men; however, it can affect both genders.
Loss of Blood
Losing blood is one of the most obvious causes of low blood pressure. Major injuries stemming from a car accident or falls, among other things, can result in open wounds or internal injuries. Both of these can cause a loss of blood that precipitates low blood pressure.
Heart Conditions
Heart conditions such as heart valve problems, heart attack or an abnormally low heart rate can all cause low blood pressure, according to the American Heart Association. Conditions like these make it difficult for the heart to pump enough to meet the needs of the body.
Hypovolemic Shock
Hypovolemic shock is a life-threatening complication of dehydration, a condition resulting in the body losing more water than it takes in. The more dehydrated a person is, the lower his blood volume becomes. This, in turn, causes a sudden drop in blood pressure. Similarly, the lower a person's blood pressure the less oxygen his tissues receive; this results in hypovolemic shock. In severe cases that are not treated, death can occur within minutes or hours, explains the Mayo Clinic.
Anaphylaxis
Anaphylaxis is a severe allergic reaction some people have to latex, insect bites or bee stings, medication such as penicillin and certain foods like peanuts. Every person's allergy and allergic reaction differs, and when some people are exposed to their allergen, low blood pressure can occur. Other symptoms include itching, hives, a swollen throat and problems breathing.
Septic Shock
Infections in the abdomen, urinary tract or lungs can often lead to septic shock. The American Heart Association explains that septic shock occurs when the bacteria responsible for these infections leave the original site and travel through the bloodstream. The bacteria makes toxins that affect the blood vessels, causing a sudden, and sometimes deadly, drop in blood pressure.
