Dehydration in adults

Dehydration in adults overview

Dehydration is a condition that occurs when the loss of body fluids, mostly water, exceeds the amount that is taken in. With dehydration, more water is moving out of our cells and then out of our bodies than the amount of water we take in through drinking.

We lose water every day in the form of water vapour in the breath we exhale and as water in our sweat, urine, and stool. Along with the water, small amounts of salts are also lost.

When we lose too much water, our bodies may become out of balance or dehydrated. Severe dehydration can lead to death.

Causes of dehydration in adults

Many conditions may cause rapid and continued fluid losses and lead to dehydration:

• High temperature, heat exposure, and too much exercise
• Vomiting, diarrhoea and increased urination due to infection
• Diseases such as diabetes
• The inability to seek appropriate water and food (an infant or disabled person, for example)
• An impaired ability to drink (someone in a coma or on a ventilator, or a sick infant who cannot suck on a bottle are common examples)
• No access to safe drinking water
• Significant injuries to skin, such as burns or mouth sores, or severe skin diseases or infections (water is lost through the damaged skin)

Symptoms of dehydration in adults

The signs and symptoms of dehydration range from minor to severe.

• Increased thirst
• Dry mouth
• Weakness
• Dizziness
• Palpitations (feeling that the heart is jumping or pounding)
• Confusion
• Sluggishness, even fainting
• Inability to sweat
• Decreased urine output: urine colour may indicate dehydration. If urine is concentrated and deeply yellow or amber, you may be dehydrated.

When to seek medical care

Seek medical advice if the person experiences any of the following:

• Increased or constant vomiting for more than a day
• Temperature over 38C (101F) that doesn't settle with temperature-lowering measures and medication
• Diarrhoea for more than two days
• Unexplained weight loss
• Decreased urine production

Seek urgent medical advice if these situations occur:

• Temperature higher than 39C (103F) that doesn't settle with temperature-lowering measures and medication
• Confusion
• Lethargy
• Headache
• Seizures
• Difficulty breathing
• Chest or abdominal pains
• Fainting
• No urine in the last 12 hours

Examinations and tests

The doctor may perform a variety of simple tests at the examination and send blood or urine samples to the laboratory. Through tests and examination, the doctor will try to identify the underlying cause or causes that led to the dehydration:

Vital signs

• High temperature, increased heart rate, decreased blood pressure, and faster breathing are signs of potential dehydration and other illnesses.
• Taking the pulse and blood pressure while the person is lying down and then after standing up for one minute can help determine the degree of dehydration. Normally, when you have been lying down and then stand up, there is a small drop in blood pressure for a few seconds. The heart rate speeds up, and blood pressure goes back to normal. However, when there is not enough fluid in the blood because of dehydration and the heart rate speeds up, not enough blood is getting to the brain. The brain senses this condition. The heart beats faster, and if you are dehydrated, you feel dizzy and faint after standing up.