Is Your Symptom a Sign of Dehydration or Something Else?

When you feel a headache (or fatigue or dizziness or mental fuzziness) come on, you may be quick to assume you’re dehydrated. Not so fast. While it’s true that these symptoms are some of the indicators that you’re not getting enough fluids, that may not be the only thing your body is trying to tell you.

“Signs of dehydration in adults and children can include headache, dizziness, tiredness, thirst, dry mouth, crankiness, dark urine, dry skin, and constipation,” says Jennifer Williams, MPH, a research scientist at Abbott specializing in dehydration and pediatric nutrition.

These symptoms are broad, and most are not specific to dehydration. “These can be signs of other medical conditions as well, so they shouldn’t be ignored,” says Rachel Lustgarten, RD, at Weill Cornell Medicine and NewYork-Presbyterian in New York City.

Here are seven medical conditions that could be the real underlying issue.

1. Dizziness, Confusion, or Headache May Signal Heatstroke or Dehydration

“Many of the same symptoms of dehydration arise when an individual is experiencing heatstroke,” says cardiologist Garth Graham, MD, MPH, director and global head of healthcare and public health at Google. Those overlapping symptoms include dizziness, confusion, and headache. (1,2) But pay attention to other indicators of heatstroke: a body temperature of at least 104 degrees F, nausea, and a racing heart rate. Dehydration and heatstroke also share some causes, such as hot weather and strenuous activity, and, to add to the confusion, being dehydrated sometimes leads to heatstroke. (2)

“Being able to tell them apart is vital,” Dr. Graham says. That’s because the seriousness of the conditions varies significantly. You don’t usually need to seek medical attention for mild dehydration because you can rehydrate on your own, but heatstroke can be deadly and is “not a health issue to be light about,” Graham says. You’ll want to call 911 if you or someone nearby appears to be suffering from heatstroke. As you wait for help to arrive, move to a cool place and do whatever you need to do to cool down, whether by dumping cold water on your body or removing excess clothing. (2)

2. Dehydration Causes Confusion, but Stroke Can, Too

Severe dehydration can lead to confusion, but confusion may also be a sign of a stroke, says Sean Hashmi, MD, a board-certified internist, nephrologist, and obesity medicine specialist practicing at Kaiser Permanente in Southern California. So how can you tell what’s really going on? Look out for symptoms unique to stroke patients. Someone having a stroke may slur his or her words, experience numbness on one side of the body, or have trouble walking. (3) When in doubt, call on a doctor for an expert opinion. “Whenever there’s a change in how a person normally behaves — and this is incredibly important among people who are older — you want to make sure you get that person evaluated so we’re not just writing it off as dehydration and, God forbid, missing something like a stroke,” Dr. Hashmi says.

3. Concussion and Dehydration Can Cause Serious Headaches

Picture this: A teenager has been playing football all afternoon in hot weather and tumbles down in a tackle. He starts experiencing headaches, which could indicate a concussion — or simply dehydration. Dana Cohen, MD, an integrative medicine doctor based in New York City and the author of Quench: Beat Fatigue, Drop Weight, and Heal Your Body Through the New Science of Optimum Hydration, says it’s important for the child to be hydrated before a doctor evaluates him. “When a doctor is trying to diagnose a concussion in a kid, which has symptoms including dizziness and headache, it’s hardly ever taken into account that dehydration has very similar symptoms,” Dr. Cohen says. “You may be misdiagnosed with a concussion early on when you were just dehydrated.” Or vice versa: A coach might assume the teen is dehydrated when in fact he may have a concussion, which requires emergency care if accompanied by vomiting, changes in behavior and coordination, or a loss of consciousness that lasts longer than 30 seconds. (4)

4. Menopause Can Cause Symptoms Similar to Dehydration

Like dehydration, menopause is usually accompanied by symptoms such as irritability and dryness. “If you’re losing estrogen, you’re drying out all over the place,” Cohen says. Hashmi says dehydration can lead to dry skin that loses its elasticity. But if you’re a woman in your 40s or 50s and notice dryness in the vaginal region, and perhaps also experience irregularities with your period, menopause could be to blame. (5) “That could be something to look into if you know you’re hydrating properly and [the dryness doesn’t go away],” Cohen says.

5. Sjogren’s Syndrome Leads to Dryness in Ways That Dehydration Does, as Well

Experiencing dry mouth, lips, and eyes can be the body’s way of telling you to take in more fluids. (6) Pay special attention to your eyes, though. Cohen says if you notice an uptick in how many eye drops you’re using, it could be Sjogren’s syndrome. This autoimmune disorder usually occurs in women over age 40. Your eyes will likely also burn, itch, or feel like there’s sand in them. (7) Your doctor will likely measure your tear production and check for a damaged cornea, which may indicate Sjogren’s syndrome and not dehydration. (7)

6. Like Dehydration, Liver Disease Can Cause Urine Irregularities

Talk to any hydration expert and he or she will tell you to pay attention to the color of your urine to know how hydrated you are. Pale yellow? You’re in the clear. But a dark color could be a sign you’re in need of some water. (1) Or, it could indicate a problem with your liver.

When bile is being blocked inside or outside the liver, which is called cholestasis, your urine may be darker than usual. Be on the lookout for other signs that something’s not right with your liver, such as pale stools or a yellow tint to your skin and eyes, which is a condition called jaundice. (8)

7. Hypothyroidism Can Cause Constipation, a Common Symptom of Dehydration

Having low thyroid hormone production, aka hypothyroidism, can result in symptoms including dry skin and constipation, which overlap with signs of dehydration, Cohen says. Other symptoms the two conditions share are fatigue and confusion. (9) Dehydration can happen to anyone, though the risk is much higher for young children and elderly people. (1,9)

The condition occurs when the body’s thyroid gland isn’t working properly, and it’s something you’ll want to get checked out. If left untreated, it could lead to infertility, obesity, or heart disease among other conditions. (9)