8 Surprising Side Effects of Dehydration That Can Make You Feel… Not So Great

Photo: Getty Images/Klaus Vedfelt
If there’s one piece of advice that health and wellness experts of all stripes like to repeat over and over again, it’s to drink enough water. Being dehydrated can lead to well-known problems like constipation, kidney problems, dry mouth, and more. That’s old news, right?

Here’s where it gets interesting, though: Dehydration can also impact how you feel in sneakier, more unexpected ways, as well. Doctors share some of the most surprising side effects to know about.

Dehydration side effects may explain why you’re experiencing…

1. Bad breath or a weird taste in your mouth

Having fresh breath isn’t only about mints and mouthwash. “If you are dehydrated, you make less saliva, and so [you] cannot fight off odor-containing bacteria in your mouth,” says Andrea Gabel, MD, a board-certified family physician. Saliva has antibacterial compounds, she explains, so a dry mouth can mean more bad-smelling bacteria hangs around.

2. Joint pain

Water is important for our joints, no matter how healthy they already feel. “Dehydration contributes to both new onset joint pain and [the] worsening of already-existing joint pain,” says Alona Pulde, MD, a family medicine physician and CEO of WeHeal. “Hydration is extremely important in keeping the joints lubricated and flexible, reducing inflammation, and preventing friction and stiffness of the joints.”

3. Muscle cramps

While stretching regularly is crucial for staying mobile, it’s not the only way to keep our muscles feeling good. “[Muscle cramps] can occur from electrolyte imbalances caused by sweating in heat or vomiting/diarrhea during an illness,” Dr. Gabel says. Drinking more water will usually solve this problem, she says, but an electrolyte beverage might also be needed.

4. Compromised skin health

If your skin hasn’t been looking or feeling too great recently, you might need to drink more water. “When the body lacks adequate water, the skin can become dry, flaky, and more prone to irritations and breakouts,” says Patrick Carter, DO, a board-certified family practitioner and the medical director of corporate locations at Prime IV Hydration & Wellness. “Dehydration reduces the skin’s ability to maintain its natural protective barrier, making it susceptible to external pollutants and irritants.”

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5. Decreased immunity and functioning

As you can probably tell, water plays a major role in many bodily functions. Giving our bodies an inadequate amount can negatively impact our blood, lymphatic systems, mucous membranes, white blood cells, and nutrient absorption, as well, according to Dr. Pulde.

“When our body is lacking vital resources, it redistributes its focus to organs necessary for survival, like our heart and lungs,” she explains. “Immunity becomes less important, and therefore suppressed.”

6. Mind and mood problems

It’s not all in your head if you find it harder to think clearly after a sweaty workout. Dr. Carter mentions difficulty concentrating, memory problems, and lower overall cognitive performance as potential side effects of dehydration. “The science behind this is related to reduced blood flow to the brain, alterations in neurotransmitter levels, and changes in brain cell activity due to dehydration,” he explains.

Dr. Gabel mentions how depression and anxiety can also pop up due to decreased blood flow, too.

Side note: Especially when you’re feeling brain fog, you may (understandably) want to turn to caffeine—but Dr. Gabel thinks that’s probably not in your best interest. “This may make it worse, as caffeine is a natural diuretic, and this can lead to worsening dehydration,” she says. You’re better off reaching for your favorite designer water bottle first.

7. Sugar cravings

Feeling in the mood for something sweet or carb-rich? Go for it! But consider drinking some water, too. Dehydration can prevent your body from regulating your blood sugar (or glucose) as effectively, meaning it can’t release that glucose to give your body energy, according to Dr. Pulde. “As a result, sugar cravings are increased in an effort to provide you with a quick energy boost,” she says.

8. More allergy and asthma symptoms

It turns out pollen floating around in the air isn’t the only allergy contributor here. “Dehydration causes an increase in histamine levels, which are what causes our allergy symptoms,” Dr. Gabel notes.

But what about asthma? Dr. Gabel says dehydration can also cause inflammation in the airways and an increase in mucus production. “This can cause asthma symptoms to worsen, such as chest tightness, wheezing, and shortness of breath,” she explains.

So what can help?

If you find yourself experiencing these dehydration side effects, your first (and most obvious) step is to make sure you're drinking enough water. What does that mean, though? According to Dr. Gabel, the “eight glasses a day” advice is a bit of a myth. “It really varies person to person,” she says. Keep in mind what causes dehydration can depend on many factors, including sleep, exercise, and dry mouth during pregnancy.

Generally speaking, she recommends a baseline of a half ounce to one ounce of water per pound of body weight (more toward the one-ounce end if you’re exercising, she clarifies).

Don’t know how much you weigh, and don’t want to know? That’s fair—just go with your best guess. You can check your urine color (ideally a light yellow, Dr. Gabel says) to make sure you're getting enough.

Dr. Gabel adds that thirst can decrease with age, so it’s not always a reliable marker. If you think you're falling behind on the hydration front, focus on incorporating a mix of water, electrolyte beverages, and hydrating foods into your diet. In other words, while water is important, there are additional options for those of us who don’t love it!

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