Causes, incidence, and risk factors
There are three main types of hypotension:
- Orthostatic hypotension, including postprandial orthostatic hypotension
- Neurally mediated hypotension (NMH)
- Severe hypotension brought on by a sudden loss of blood (shock), infection, or severe allergic reaction
NMH most often affects young adults and children. It occurs when a person has been standing for a long time. Children usually outgrow this type of hypotension.
Low blood pressure is commonly caused by drugs such as:
- Anti-anxiety medications
- Certain antidepressants
- Heart medicines, including those used to treat high blood pressure and coronary heart disease
- Medications used for surgery
- Advanced diabetes
- Anaphylaxis (a life-threatening allergic response)
- Changes in heart rhythm (arrhythmias)
- Heart attack
- Heart failure
- Shock (from severe infection, stroke, anaphylaxis, blood loss, or heart attack)
- Blurry vision
- Fainting (syncope)
Signs and tests
The doctor will ask questions, including:
- What is your normal blood pressure?
- What medications do you take?
- Have you been eating and drinking normally?
- Have you had any recent illness, accident, or injury?
- What other symptoms do you have?
- Did you faint or become less alert?
- Do you feel dizzy or light-headed when standing or sitting after lying down?
- Basic metabolic panel
- Blood cultures to check for infection
- Complete blood count (CBC), including blood differential
- X-ray of the abdomen
- X-ray of the chest
If you have signs or symptoms of low blood pressure, you may need treatment. Treatment depends on the cause of your low blood pressure. Severe hypotension caused by shock is a medical emergency. You may be given blood through a needle (IV), medicines to increase blood pressure and improve heart strength, and other medicines, such as antibiotics. For more details, see the article on shock.
If you have orthostatic hypotension caused by medicines, your doctor may change the dose or switch you to a different drug. DO NOT stop taking any medicine before talking to your doctor. Other treatments for orthostatic hypotension include increasing fluids to treat dehydration or wearing elastic hose to boost blood pressure in the lower part of the body.
Those with NMH should avoid triggers, such as standing for a long period of time. Other treatments involve drinking plenty of fluids and increasing the amount of salt in your diet. (Ask your doctor about specific recommendations.) In severe cases, medicines such as fludrocortisone may be prescribed.
- Injury from falls due to fainting
Severe hypotension starves your body of oxygen, which can damage the heart, brain, and other organs. This type of hypotension can be life threatening if not immediately treated.
Calling your health care provider
If low blood pressure causes a person to pass out (become unconscious), seek immediate medical treatment or call the local emergency number (such as 911). If the person is not breathing or has no pulse, begin CPR.
Call your doctor immediately if you have any of the following symptoms:
- Black or maroon stools
- Chest pain
- Dizziness, lightheadedness
- Fever higher than 101 degrees Fahrenheit
- Irregular heartbeat
- Shortness of breath
- Burning with urination or other urinary symptoms
- Cough with phlegm
- Inability to eat or drink
- Prolonged diarrhea or vomiting
- Avoiding alcohol
- Avoiding standing for a long time (if you have NMH)
- Drinking plenty of fluids
- Getting up slowly after sitting or lying down
- Using compression stockings to increase blood pressure in the legs