How does dehydration affect blood pressure and heart rate

How low is too low for blood pressure?

Within certain limits, the lower your blood pressure reading is, the better. There is also no specific number at which day-to-day blood pressure is considered too low, as long as none of the symptoms of trouble are present.

Symptoms of low blood pressure

Most doctors will only consider chronically low blood pressure as dangerous if it causes noticeable signs and symptoms, such as:

• Dizziness or lightheadedness
• Nausea
• Fainting (syncope)
• Dehydration and unusual thirst
• Dehydration can sometimes cause blood pressure to drop. However, dehydration does not always cause low blood pressure. Fever, vomiting, severe diarrhea, overuse of diuretics and strenuous exercise can all lead to dehydration, a potentially serious condition in which your body loses more water than you take in. Even mild dehydration (a loss of as little as 1 percent to 2 percent of body weight) can cause weakness, dizziness and fatigue.
• Lack of concentration
• Blurred vision
• Cold, clammy, pale skin
• Rapid, shallow breathing
• Fatigue
• Depression

Underlying causes of low blood pressure

Low blood pressure can occur with:

• Prolonged bed rest
• Pregnancy: During the first 24 weeks of pregnancy, it’s common for blood pressure to drop.
• Decreases in blood volume: A decrease in blood volume can also cause blood pressure to drop. A significant loss of blood from major trauma, dehydration or severe internal bleeding reduces blood volume, leading to a severe drop in blood pressure.
• Certain medications: A number of drugs can cause low blood pressure, including diuretics and other drugs that treat hypertension; heart medications such as beta blockers; drugs for Parkinson’s disease; tricyclic antidepressants; erectile dysfunction drugs, particularly in combination with nitroglycerine; narcotics and alcohol. Other prescription and over-the-counter drugs may cause low blood pressure when taken in combination with high blood pressure medications.
• Heart problems: Among the heart conditions that can lead to low blood pressure are an abnormally low heart rate (bradycardia), problems with heart valves, heart attack and heart failure. Your heart may not be able to circulate enough blood to meet your body’s needs.
• Endocrine problems: Such problems include complications with hormone-producing glands in the body’s endocrine systems; specifically, an underactive thyroid (hypothyroidism), parathyroid disease, adrenal insufficiency (Addison’s disease), low blood sugar and, in some cases, diabetes.
• Severe infection (septic shock): Septic shock can occur when bacteria leave the original site of an infection (most often in the lungs, abdomen or urinary tract) and enter the bloodstream. The bacteria then produce toxins that affect blood vessels, leading to a profound and life-threatening decline in blood pressure.
• Allergic reaction (anaphylaxis): Anaphylactic shock is a sometimes-fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, to certain foods such as peanuts or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.
• Neurally mediated hypotension: Unlike orthostatic hypotension, this disorder causes blood pressure to drop after standing for long periods, leading to symptoms such as dizziness, nausea and fainting. This condition primarily affects young people and occurs because of a miscommunication between the heart and the brain.
• Nutritional deficiencies: A lack of the essential vitamins B-12 and folic acid can cause anemia, which in turn can lead to low blood pressure.

If you notice a sudden decline in blood pressure

A single lower-than-normal reading is not cause for alarm, unless you are experiencing any other symptoms or problems. If you experience any dizziness, lightheadedness, nausea or other symptoms, it’s a good idea to consult with your healthcare provider. To help with your diagnosis, keep a record of your symptoms and activities at the time they occurred.

Is low blood pressure related to low heart rate? Find out.

Written by American Heart Association editorial staff and reviewed by science and medicine advisers. See our editorial policies and staff.

Here in the South, July and August are two of the most sweltering months and it is important to take care of our bodies during times of extreme heat. One of the most common summertime dangers is dehydration. It is essential to remember that dehydration is dangerous not only to people, but pets and animals as well.

A common mistake many people make is grabbing an ice-cold soda or energy boosting drink instead of water, but these beverages can actually cause you to become even more dehydrated. Listed below are ten dangers of dehydration that you should be aware of for yourself, loved ones, and pets:

1. Muscle Cramps- You don’t have to be an athlete to get muscle cramps. Those who are minimally active and drink insufficient fluids are equally prone to cramps. Dehydration causes hypersensitivity and involuntary contraction of muscles.

2. Depression- The brain  requires 85% water - more than any other organ in the body. Water deficiency in brain cells can result in an immediate cut down of the brain’s energy supply, which leads to fatigue, lethargy, and depression.

3. Constipation- After food is eaten, it is broken down in the small intestine and the non-essential portion of the food gets converted to waste. Dehydration causes the intestinal cells to extract water from the food waste in the intestines, causing the waste to become hard, leading to constipation.

4. Hypertension- High blood pressure is common in people who are chronically dehydrated. When the body’s cells lack water, the brain sends a signal to the pituitary glad to secrete vasopressin, a chemical that causes constriction of the blood vessels. This causes blood pressure to increase which leads to hypertension.

5. Kidney Stones- Dehydration can cause urine to become concentrated which causes minerals from the urine to accumulate in a crystal formation. These crystal formations get deposited in the kidneys, causing kidney stones.

6. Uremia- Adequate water in the body helps the kidneys filter waste easily while diluting urine. Insufficient water in the body makes it difficult for the kidneys to separate necessary amounts of waste away from the urine, allowing waste that should have been excreted to get trapped and circulated throughout the body. 

7. Gallstones- Similarly to blood vessels compressing, dehydration can also cause contraction of bile ducts in the liver. These contractions can result in the formation of gallstones.

8. Kidney Disease- When your body is dehydrated, the kidneys reduce urine formation that causes the capillaries to constrict in areas like the heart and brain, resulting in high blood pressure. The combination of high blood pressure and urine retention causes serious kidney damage and could eventually lead to kidney disease.

9. Joint Complications- Dehydration causes the cartilage in joints to rub against each other, causing weakening and wearing over time. However, with adequate water supply and the formation of new cells, the cartilage can be repaired. Lack of water increases the delay of repair to these damaged joints and over time the cartilage can wear out completely. 

10. Death- Water totals about 60% of the body’s total weight. Every single bodily function and process needs water to remain active and healthy. Severe dehydration can be fatal so it is important to notice all of the other warning symptoms and do something to fix them! 

Will your blood pressure go up if you are dehydrated?

Does dehydration cause high blood pressure or low blood pressure?

Can dehydration cause high blood pressure and high heart rate?

Can dehydration cause low blood pressure and high heart rate?

Can dehydration make your heart rate higher?