We’ve all heard the stern admonitions about how important it is to drink plenty of water. Water is essential for good skin and keeping your kidneys working. Did you know that a lack of water in the short term is not that serious but it can lead to real issues — issues that may require hospitalization? Dehydration is a serious condition.

According to the Mayo Clinic, “Dehydration occurs when you use or lose more fluid than you take in, and your body doesn’t have enough water and other fluids to carry out its normal functions.”

The best way to hydrate is to drink plenty of water; most experts recommend 6-8 glasses a day. Of course, sweating and other factors (like infection) can mean more water is needed. Thirst isn’t always a reliable indicator of dehydration. Older folks usually don’t feel thirsty until dehydration has already set in.

If you’re wondering whether or not you’re drinking enough water, here are some ways to tell if you are dehydrated:

Headache

Headaches are often a symptom of dehydration. The drop in blood volume when there is a lack of hydration causes the brain’s oxygen levels to be reduced and the blood vessels dilate painfully.

Urine appearance and output

Most of us rarely pay much attention to our urine output or its appearance, but we should. Healthy urine is light yellow or clear. If your urine is medium yellow or dark, it means that you aren’t drinking enough water.

If you are dehydrated, it’s possible you won’t have to urinate as often, either. Or you may urinate more often — because of diabetes or because you are taking medications that cause excessive urination.

Dry mouth and eyes

If your eyes are dry and crying produces no tears, you are likely dehydrated. Similarly, if your mouth is dry, that’s another symptom. Saliva production will be less if you’re dehydrated.

Low energy

When the body is dehydrated only the most vital organs will get the needed fluids, so the other organs become sluggish. A lack of energy may be caused by dehydration.

Cramping

If you are outside a lot doing work or sports activities, you may sweat out the water you need to hang onto. Painful muscle cramps can result. Cramping signals that your body doesn’t have enough hydration. Not all cramps are caused by sodium depletion and fluid loss, but drinking water or sports drinks while outside is a good way to reduce the chances of painful cramps.

Hunger

Have you ever eaten and then immediately felt hungry, even though you know you ate enough? The same part of the brain that regulates hunger also controls thirst, and sometimes your body confuses the two.

Dry skin

Most of us get dry skin in wintertime when the heat comes on multiple times. Dry skin may be caused by a number of factors. However, in cases of dehydration, the body will use its limited supply of water for internal organs and leave the skin high and dry. If your skin is very dry, pay attention to other signs of possible dehydration and take steps.

Illness

You know how, when you’re sick doctors usually advise to rest and drink plenty of fluids? When your body runs a fever, dehydration can occur quickly, and the higher the fever, the worse the dehydration. Vomiting and diarrhea often result in dehydration because the body cannot hold onto fluids.

Severe dehydration is no joke. In addition to the above symptoms, dehydration can lead to a loss of electrolytes and drinking water may simply not solve the problem. Hospitalization may be necessary, especially when vital minerals like sodium and potassium are critically low. In extreme cases, death may occur. This is especially true for babies or young children, or senior citizens.

Pay attention to your hydration levels, and be sure to drink plenty of fluids.