How Long Does It Take to Rehydrate After Dehydration?

If your dehydration is mild to moderate, it is possible to rehydrate with home care within a few hours.

Drinking enough water is important for a wide variety of reasons. Being well-hydrated helps you regulate your body temperature, keeps your joints lubricated, prevents infections, gets nutrients to your cells, and keeps your organs functioning smoothly. Good hydration also improves the quality of your sleep, your cognition, and even your mood.

Your body is approximately 50% to 75% water, most of which is found inside your cells. A newborn’s body mass is closer to 75% water, while adults can be up to 60%. You are constantly losing water through a variety of ways. You replenish it through the water you drink and some foods that you eat.

Dehydration is when more water leaves your body than enters it. When your body does not have enough water, it does not function as well. Dehydration can range from mild to severe.

Symptoms of mild to moderate dehydration include:

• Thirst
• Dry mouth
• Fatigue
• Dry skin
• Decreased urination
• Dizziness
• Lightheadedness
• Headache

Symptoms of severe dehydration include:

• Excessive thirst
• Lack of sweat production
• Low blood pressure
• Rapid heart rate
• Rapid breathing
• Sunken eyes
• Shriveled skin
• Dark urine
• Delirium
• Unconsciousness/fainting

Infants and young children may have additional symptoms including

• No tears when crying
• No wet diapers for 3 hours or more
• Sunken soft spot on top of the head
• Listlessness or irritability

Severe dehydration at any age is a serious medical emergency and can be fatal. Contact your doctor if you are experiencing any of these symptoms. 

Your body can lose water in a variety of ways. If the water is not replaced, you will become dehydrated. Some of the most common causes of dehydration are:

• Exercise and sweating
• Diarrhea
• Vomiting
• Urinating too much (caused by medication, alcohol, or metabolic disorder)
• Fever
• Not drinking enough fluids
• Diabetes
• Severe burns

Other factors that can make you more susceptible to dehydration include warm weather and high altitude. 

Anyone is vulnerable to dehydration. However, there are certain groups of people that are more likely to experience the condition including:

• People working outdoors, especially in the sun or heat
• Older adults
• Infants and young children
• People living at higher altitudes
• Athletes

People with some chronic conditions (including kidney disease, alcoholism, diabetes, or adrenal gland disorders).

There is no single test to diagnose dehydration, and you won’t always need to see a doctor. If you do go see a doctor, your doctor will use both a physical and mental exam to determine if you are dehydrated. 

Physical symptoms that your doctor might check for include low blood pressure, a rapid heart rate, and high body temperature. If you’re worried about why you became dehydrated, you can ask your doctor about possible underlying conditions, and your doctor may want to run a few more tests if they agree there’s reason for concern.

It’s also likely that your doctor will ask about your activity and history, including what led to your dehydration and when you last drank water.

Preventing dehydration

Experts recommend that men drink around 125 ounces (just over 15 cups) of fluid each day and that women drink around 90 ounces (over 11 cups). This includes both fluids — like water — that you drink, as well as water-rich foods like fresh fruit and vegetables.

If you are engaging in vigorous exercise, in a hot environment, or at a high altitude, you may need more than this to stay fully hydrated. Other tips to avoid dehydration include taking breaks in a cool, shady place and limiting your intake of alcohol, sugar, and caffeine.

Rehydrating after dehydration

The severity of your dehydration will influence how long it takes to return to a well-hydrated state. If your dehydration is mild to moderate, it is possible to rehydrate with home care within a few hours. Many mild cases of dehydration can be resolved by drinking a generous amount of water. If you need to replace electrolytes as well — after intense exercise, diarrhea, or vomiting — you can drink a sports drink or electrolyte solution to speed up the process.

Young children who are dehydrated can also replenish electrolytes and fluid with an oral rehydration solution (like Pedialyte). 

If your dehydration is severe, seek medical care. Your doctor may administer fluid intravenously (IV) to rehydrate your body quickly.

If dehydration is not treated, it can lead to very serious complications or even death. Complications can include:

• Low blood volume (hypovolemic shock)</li>
• Low blood pressure
• Seizures due to electrolyte imbalance
• Kidney problems or failure
• Heat injury (heat cramps, heat exhaustion, or heat stroke)