Dehydration Symptoms (Mild, Severe) and Signs in Adults

You can recognize dehydration, a lack of water in your body, from a combination of symptoms, such as thirst, dry mouth, dark urine and sudden loss of weight.

This article explains symptoms of dehydration and how to differentiate between dehydration and conditions with similar symptoms.

Main Symptoms and Signs of Dehydration

1. Thirst

Thirst is a typical but not necessary early and reliable symptom of dehydration. Thirst may appear only after a water loss that results in a 2% weight loss ^[2].

You can be severely dehydrated and may or may not be thirsty. Older people and children are often less aware of thirst. Some people may confuse thirst for hunger ^[9].

2. Dry Mouth

When dehydrated, you will usually have dry mouth. Note, that you can also have dry mouth due to dry air, breathing through the mouth, anxiety, alcohol drinking or taking certain medications.

3. Decreased Urination and Dark Yellow Urine

Excretion of only a small amount of dark yellow urine in the morning and less frequent urination during the day are typical symptoms of dehydration ^[1].

There are few exceptions; for example, in diabetes mellitus and diabetes insipidus, you can be dehydrated but still excrete a large amount of clear urine. On the other hand, when not dehydrated, you can have strong yellow urine due to eating certain foods, multivitamin supplements or having liver disease.

4. Pounding Heart

In dehydration, your adrenal glands increase the secretion of the hormone epinephrine (adrenaline), which stimulates the heart in order to maintain normal blood pressure; you can feel this as pounding heart (palpitations), especially at night.

5. Poor Skin Turgor

Dehydration results in the decreased elasticity of the skin, medically known as poor skin turgor. When well hydrated, your skin at the back of the hand should recoil in less than half of a second after you pinch and release it, but when dehydrated, the skin fold can persist for few seconds or even minutes.

Below is a detailed list of symptoms that can occur in different dehydration stages.

6. Sudden Weight Loss

With every liter of water lost, you lose 1 kilogram (2.2 lbs) of weight. Sudden weight loss within few hours to days is more likely due to water than fat loss.

Below is a detailed list of possible symptoms in mild, moderate and severe dehydration.

Dehydration Symptoms by Severity

Mild Dehydration

Early symptoms ^[4]:

Mild thirst, dry mouth
Urine: strong yellow
Slight tiredness, insomnia, anxiousness
Decreased appetite (anorexia) or hunger
Constipation

First warning clinical signs ^[1]:

Sudden loss of weight by 1-3%
Slightly increased heart rate
Skin turgor prolonged by 0.5-2 seconds

Moderate Dehydration

Symptoms ^[9,13,16,17]:

Dry, cracked lips, itchy throat
Difficulty swallowing
Urine: orange or amber; burning urination
Feeling cold
Fatigue, dizziness, difficulty concentrating, impaired memory
Moderate headache
Nausea, vomiting, morning sickness (in pregnant women)
Other: depression, nervousness, excessive sensitivity to light (photophobia)

Signs ^[1,6,8,21]:

Sudden loss of weight by 3-6%
Dry, sunken eyes; dark circles or bags under the eyes due to localized edema
White, yellow or swollen tongue, mouth sores
Skin turgor prolonged by 2-10 seconds
Heart rate: increased to 60-100/min (tachycardia)
Breathing rate: increased to >28/min
Low-grade fever

Severe Dehydration

Symptoms ^[13,14,15]:

Extreme thirst (or no thirst at all)
Urine: tea-colored or brown; painful, minimal or absent urination
No sweating despite a high ambient temperature, dry itchy skin
Lethargy, fainting, confusion, delirium, hallucinations, seizures
Severe headache or migraine
Blurred vision, temporary vision loss (blindness)
Tingling and numbness in the fingertips (due to hyperventilation)

Signs ^[1,7,8]:

Sudden loss of body weight by more than 6%
Skin: pale, wrinkled, dry and cool, skin turgor prolonged from 10 seconds to several minutes
Breathing: increased, decreased or difficulty
Heart rate: can exceed 140/min; faint pulse
Body temperature: normal (increased in infections or heat stroke)
Blood pressure: normal (decreased in hypovolemic shock)
Somnolence, coma

Extreme Dehydration

In adults, dehydration with a loss of 10-15% of body weight can result in death ^[2].

Symptoms Not Typical of Dehydration

In dehydration, urine is yellow or tea-colored and sometimes cloudy. The urine that is only cloudy, but not yellow or dark, is not caused by dehydration but, for example, by a high-protein diet, urinary tract infection or kidney inflammation.

Blood in the urine can result from the infection, inflammation, cancer or injury of the urinary tract, but less likely from dehydration. However, some athletes may notice blood in the urine, which may be related to dehydration ^[10].

Even severe dehydration by itself does not necessarily cause muscle cramps, such as calf cramps in endurance athletes ^[11,12]. Anyway, some doctors still believe dehydration in combination with muscle fatigue causes leg cramps ^[35].

Eye twitching does not result from dehydration itself but possibly from the accompanying disorders, such as low blood potassium levels (hypokalemia). Hands shaking (tremors) is also not typical for dehydration.

In severe, but not likely in mild or moderate dehydration, red, bloodshot eyes may be due to irritation of a dry cornea.

Dehydration probably does not cause the swelling of the lymph nodes in the neck or armpits. It is possible that normal lymph glands are more palpable in dehydration due to shrinkage of the surrounding tissues, though.

Dehydration as such does not likely cause kidney pain but acute kidney failure due to severe dehydration can ^[20]. Chronic dehydration is a risk factor for kidney stones that can cause flank pain ^[22].

If you are otherwise healthy, dehydration alone will unlikely cause chest pain. However, dehydration can worsen chest pain (angina pectoris) if you have coronary heart disease.

Symptoms that can be associated with problems caused by dehydration:

Bloating, stomach pain or cramps can be due to dehydration-related constipation ^[19].
Cough can be due to dry, scratchy throat.
Nosebleeds can be due to dry nose.
Ringing in the ears or tinnitus can occur in low blood pressure ^[3].
Yawning can be due to impaired sleep.

Skin rash, jaundice, lower back, leg or knee pain are also not directly associated with dehydration.

References

Dehydration Symptoms and Signs