Recognizing Low Blood Pressure Symptoms and its Causes

It is important to recognize low blood pressure symptoms. Low blood pressure is a condition in which the force of blood pushing against the artery walls is too low. 

Low blood pressure symptoms: what are they?^1-3 

Blood pressure is the pressure of the blood in your arteries, the vessels that carry blood from your heart to your brain and the rest of your body. When your blood pressure drops, your heart rate increases and blood vessels in other parts of your body constrict to help maintain blood pressure. If your heart rate does not increase enough, or your blood vessels do not constrict enough, your blood pressure will fall. This is what we call low blood pressure or hypotension. 

Blood pressure is measured in millimeters of mercury or mm Hg. In general, low blood pressure is a reading lower than 90/60 mm Hg. 

Whereas it might cause no symptoms, low blood pressure symptoms may include: 

• Blurred or fading vision 

• Dizziness or feeling lightheaded

• Fainting

• Fatigue 

• Nausea 

• Weakness  

• Confusion 

• Trouble concentrating 

• Upset stomach 

If you experience any of these signs and symptoms, speak to your doctor. 

It is worth noting that extreme low blood pressure can lead to a condition known as shock, for which symptoms include: 

• Confusion, especially in older people 

• Cold, clammy skin 

• Decrease in skin color, also called pallor 

• Rapid, shallow breathing

• Weak and rapid pulse 

What are the reasons for low blood pressure?¹ 

It is important to find out what is causing low blood pressure symptoms so that it can be treated, if needed. 

First, blood pressure varies throughout the day. Indeed, it depends on: 

• Body position: standing up from sitting or lying down—this is a sign of a type of low blood pressure called postural hypotension, also known as orthostatic hypotension

• Breathing

• Food and drink: more blood flows to your digestive system afterwards
• Medicines
• Physical condition 

• Stress

• Time of day: blood pressure is usually lowest at night and rises sharply on waking

Low blood pressure has various causes, such as some health conditions or the use of certain medicines. But big drops can be life-threatening. These can happen for reasons such as serious bleeding, serious infections, or allergic reactions. 

Conditions that can cause low blood pressure

Medical conditions that can be the reasons for low blood pressure include: 

• Pregnancy: low blood pressure is common in pregnancy and is not usually a cause for concern. Changes during pregnancy cause blood vessels to expand quickly, which may then cause low blood pressure symptoms in women. Indeed, low blood pressure is common in the first 24 weeks of pregnancy. After a person gives birth, blood pressure usually returns to the level that it was before pregnancy. 

• Heart and heart valve conditions: a heart attack, heart failure, heart valve disease, and a slow heart rate called bradycardia can cause low blood pressure symptoms. 

• Hormone-related diseases: also called endocrine conditions, such as Addison disease that affect certain glands that make key hormones, such as cortisol which help to regulate blood pressure. If you do not make enough of them, it may cause low blood pressure symptoms. 

• Hypoglycemia / diabetes: low blood sugar, or hypoglycemia, may lower blood pressure. So might diabetes. 

• Dehydration: when the body does not have enough water, the amount of blood in the body declines. This can cause low blood pressure symptoms. Fever, vomiting, severe diarrhea, overuse of diuretic medicines, and strenuous exercise can lead to dehydration.  

• Blood loss: losing a lot of blood also reduces blood volume, leading to a severe drop in blood pressure. Causes of serious blood loss include injuries and internal bleeding. 

• Severe infection: when an infection in the body enters the bloodstream, it can lead to a life-threatening drop in blood pressure called septic shock. Another name for an infection that happens when germs get into the blood and spread is septicemia. 

• Severe allergic reaction, also called anaphylaxis: symptoms include a sudden and large drop in blood pressure. 

• Lack of nutrients in the diet: low levels of vitamin B12, folate and iron can keep the body from making enough red blood cells. A lack of healthy red blood cells is called anemia and can lead to low blood pressure symptoms. 

Medications that can cause low blood pressure

Some medicines can cause low blood pressure symptoms, including: 

• Heart and high blood pressure medicines: these include diuretics, alpha-blockers and beta-blockers 

• Medicines for Parkinson disease: for example, pramipexole and medicines that contain levodopa 

• Certain types of depression medicine called tricyclic antidepressants: for example, doxepin and imipramine 

• Medicines for erectile dysfunction: for example, sildenafil or tadalafil, especially when taken with the heart medicine nitroglycerin

Risk factors of low blood pressure symptoms

Risk factors for hypotension include:

• Age: drops in blood pressure when standing up or after eating occur mainly in adults older than 65 years of age.
• Alcohol or illegal drugs: either of these may raise the risk of low blood pressure.