Written by Karen Hovav, MD, FAAP | Reviewed by Sophie Vergnaud, MD Updated on April 25, 2023
Key takeaways:
- Feeling thirsty is your body’s way of letting you know that you need more water. It’s a natural response to protect you against dehydration.
- Sometimes, excessive thirst can be caused by an underlying medical condition, like diabetes, anemia, or high calcium levels.
- Pregnancy, breastfeeding, certain foods, and some medications can also cause excessive thirst.
- Water is the best way to hydrate. Other drinks — from milk, coffee, and tea to fruit juices, sports drinks, and sparkling water — can also help with hydration. But take care to limit drinks that are high in sugar.
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To quench your thirst, there’s nothing like a cool cup of water on a hot day. Feeling thirsty is usually your body’s way of letting you know that it’s getting dehydrated and you need more water to stay in balance. But what does it mean if you’re thirsty all the time?
According to Sonal Chaudhry, MD, assistant professor of endocrinology, increased thirst can be a common and natural reaction to dehydration, increased salt intake, or certain medications. Water makes up about 60% of your body. And the body has a very complex system for keeping just the right amount of fluid at any given time. So the body can send a message to the brain that it’s thirsty, which is your cue to drink.
Sometimes it’s obvious what’s making you thirsty. For example, if you’ve been sweating a lot on a hot day, your body will need more fluid. Other times it might not be so clear why your body wants extra hydration, and it may be a sign of an underlying medical issue. If you feel thirsty all the time, read on to learn about the top causes of thirst, and when to consider reaching out to a healthcare provider.
1. Dehydration
Dr. Chaudhry told us, “Dehydration is a very common cause of increased thirst.” People usually start to feel thirsty when the body loses about 1% to 2% of body water. Dr. Chaudhry adds, “The body has receptors that sense changes in fluid volume and trigger a thirst response.” So, if there’s a chance you could be dehydrated, listen to your body’s cues and drink until your thirst is quenched.
Typically, dehydration is either caused by not drinking enough or losing more fluids than usual.
Common causes of dehydration include:
- Sweating a lot, from exercise or hot weather
- Sickness, like with an infection
- Diarrhea
- Vomiting
- Peeing more than usual
- Less fluid intake than usual (due to an illness, forgetfulness, or a busy day)
2. Food
Certain foods are more likely to make you feel thirsty. Here are some common foods that trigger thirst:
- Salty foods, including many processed foods
- Spicy foods, which can make you sweat more
- High protein diets, which can lead to dehydration
3. Diabetes mellitus
People with diabetes have too much glucose (sugar) in their bloodstream. That extra blood glucose triggers pathways to make you feel thirsty. This is a cue to hydrate, which helps bring glucose levels back down to normal. The body also produces more urine, which flushes out extra glucose. That’s why the signs of uncontrolled or undiagnosed diabetes are excessive thirst and excessive urination.
So, if you’re peeing more and more and you’re constantly thirsty even though you’re drinking a lot, reach out to your healthcare provider for a diabetes test.
4. Medication
If you’re taking a medication and start feeling extra thirsty, it’s important to check if a medication side effect might be the cause. Here are a few examples of medications that can lead to increased thirst:
- Diuretics: Also called “water pills,” these make you pee more so that your body can get rid of extra fluid. They’re used to treat conditions like high blood pressure, congestive heart failure, or body swelling (edema). But they can lead to dehydration and increased thirst.
- Lithium: This medication is sometimes prescribed to treat bipolar disorder. Since lithium is an electrolyte, like sodium, people who take it need to drink more water to keep their bodies in balance.
- SGLT2 inhibitors: This is a class of medications used to treat diabetes mellitus by helping the body get rid of extra glucose in the urine. This makes the body pee more and can make you feel constantly thirsty.
- Chemotherapy: This can cause a lot of vomiting and diarrhea, which can lead to increased thirst. It can also cause inflammation in the mouth, which makes it harder to drink water.
5. Pregnancy
During pregnancy, your thirst threshold is lowered. This is nature’s way of making sure you drink extra fluid to support the needs of your changing body and the growing fetus. Sometimes people can also feel dehydrated from excess vomiting associated with pregnancy hormones (“morning sickness”).
6. Breastfeeding
Breastfeeding can trigger intense thirst, too. Again, this is nature’s way of making sure you get extra water to produce enough milk for the baby. Breastfeeding triggers the release of oxytocin, often called the “love hormone” because it can help create bonding and feelings of well-being. But research suggests that oxytocin may also trigger thirst as a way to replenish the fluid that’s lost as breast milk.
7. Menopause
According to Dr. Chaudhry, hormone changes of early menopause (perimenopause) and menopause can cause increased thirst. This happens because of extra fluid losses from hot flashes and night sweats.
And the body may not be as good at self-regulating its own hydration during menopause. During the transition to menopause, Dr. Chaudhry recommends staying well hydrated and drinking when you feel thirsty, especially when exercising.
8. Anemia
Anemia is a condition in which levels of red blood cells are lower than normal. Lots of different things can cause anemia. But the symptoms of severe anemia are the same no matter the cause:
- Increased thirst
- Dizziness
- Fatigue
- Weakness
- Cold hands and feet
- Pale skin
9. High blood calcium levels
Hypercalcemia, or high blood calcium levels, can make you feel thirsty. This happens because the body makes more urine to try to get rid of the extra calcium in the urine.
High calcium levels are often caused by a problem with the parathyroid glands, tiny glands on top of the thyroid gland in the neck. If the parathyroid gland becomes hyperactive, it can cause the calcium level to get too high. There are also some cancers that can lead to high calcium levels and excessive thirst.
10. Diabetes insipidus
Diabetes insipidus is a rare condition in which the body makes too much urine. It’s not related to the more common types of diabetes. In diabetes insipidus, the kidney can’t concentrate urine if you’re dehydrated, so you pee out large amounts of dilute urine all the time.
While people normally make around 1 to 3 quarts of urine per day, a person with diabetes insipidus can make up to 20 quarts of urine a day. This causes extreme and constant thirst.
Testing for diabetes insipidus often starts with a urine test to measure the concentration of your urine. Your healthcare provider may also order a water deprivation test. To do this, you stop drinking fluids for several hours and have blood and urine tests done during that time.
Does it matter what you drink when you feel thirsty?
Water is the best and healthiest option for hydration. Water doesn’t have calories or added sugar, so it’s the best choice for overall health, too. This is especially true for anyone who is trying to maintain a healthy weight.
Studies have compared the hydrating power of water with other drinks. The results? There’s actually not much difference.
A 2016 randomized trial looked at 13 different kinds of beverages and found that most liquids were equally effective at rehydration. This included water, coffee, and tea as well as orange juice, sparkling water, sports drink, and beer. But the study found that cow’s milk and oral rehydration solutions were the best at keeping people hydrated for longer.
Sports drinks vs. energy drinks vs. oral rehydration solutions
With so many options for hydration, it can be challenging to figure out which type of drink is best for you. Water is always best, but there may be some situations in which you might consider a sports drink, energy drink, or oral rehydration solution. Here’s the difference between these three types of drinks — and when to choose one over another.
Sports drinks
Sports drinks have added electrolytes, carbohydrates (sugar), and sometimes nutrients, like the B vitamins. Electrolytes may be helpful if you’re doing a high-intensity workout for more than an hour.
When you exercise vigorously, you can lose electrolytes in your sweat, which a sports drink can help replenish. But, if you’re not doing high-intensity exercise, it’s best to skip on the sports drink. It’s just another sugary drink with no nutritional value.
Energy drinks
Caffeine is often the main ingredient in energy drinks. But energy drinks often contain other ingredients, like vitamins and sugar. There’s some evidence that the caffeine in energy drinks can help improve physical endurance and mental alertness, but there are also risks. The amount of caffeine in energy drinks can vary widely, and it isn’t always easy to tell just how much caffeine an energy drink contains.
Large amounts of caffeine in energy drinks can lead to:
- Heart complications, like an irregular heart beat or fast heart rate
- Anxiety
- Sleep problems
- Digestive problems
- Dehydration
Energy drinks are especially problematic in kids and teenagers because their nervous system and cardiac system are still developing. The American Academy of Pediatrics recommends that adolescents and children avoid energy drinks entirely. But 30% to 50% of adolescents report drinking them.
Oral rehydration solutions
Oral rehydration solutions (ORS) are carefully designed to treat dehydration. They’re typically used to safely rehydrate someone with diarrhea or vomiting. ORS has a precise balance of sugar and salt that makes it easier for the body to absorb electrolytes and water.
You can get an ORS as a ready-to-go powder in the store, or you can make your own ORS at home with a few simple ingredients. Either way, it’s very important not to add any more sugar or salt to an ORS. Too much sugar can make diarrhea worse, and too much salt can be very harmful — especially to a child.
The bottom line
Feeling thirsty is your body’s way of making sure you don’t get dehydrated. This lets you keep your fluids in balance and stay healthy. But, if you’re feeling thirsty all the time, it could be a sign that your body is working hard to keep itself in a healthy balance. In other words, something else might be going on. Reach out to a healthcare provider if you’re thirsty even though you’re rehydrating, or if you’re urinating a lot. Other signs to see a primary care provider are changes in weight, vision, or energy level.
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