Conditions and symptoms
What Is Dehydration? Why Medicine Labels Mention It
Dehydration · say it: dee-hy-DRAY-shunAlso written: fluid loss, volume depletion, hypovolemia, dehydrated
Short answer
Dehydration means the body has lost more fluid than it has taken in, so it does not have enough water to work normally.
What it means
Dehydration happens when the body loses more water than it takes in, for example through vomiting, diarrhea, fever, heat, sweating or not drinking enough. Signs include thirst, dark or little urine, dry mouth, tiredness and dizziness. Severe dehydration, with confusion, very little or no urine, fainting or a fast heartbeat, needs urgent medical help. Babies and older people can become dehydrated quickly.
Medicine labels mention dehydration because it changes how some medicines act. Diuretics can cause it. SGLT2 inhibitors, ACE inhibitors, angiotensin receptor blockers, metformin, NSAIDs and lithium can be riskier when you are dehydrated, because they can affect the kidneys or build up. Some labels advise 'sick day' care: talk to your doctor or pharmacist about pausing certain medicines during vomiting or diarrhea.
Dehydration is not the same as low sodium (hyponatremia) or other electrolyte problems, though they can happen together.
Where you may see it
- 'Warnings' sections of diuretic, SGLT2 inhibitor and lithium labels
- Leaflets: 'Drink plenty of fluids' or 'Tell your doctor if you have severe vomiting or diarrhea'
- Emergency department notes and blood tests (urea, creatinine)
📄 How it looks on a report
Assess volume status and correct volume depletion before initiating treatment, particularly in elderly patients.
🙅 What it does not mean
- Thirst is not the only sign; older people may not feel thirsty.
- Drinking huge amounts of water is not always the answer; the right amount depends on your health.
- It does not mean you should stop medicines on your own; ask which ones to pause when ill.
🎯 Check yourself
Which of these is the right meaning of “Dehydration”?
🗒️ Questions to ask your doctor
💊 Medicines whose labels mention “Dehydration”
Plain-English explanations of each medicine, from its official FDA label.
- Dapagliflozin
a sodium-glucose cotransporter 2 (SGLT2) inhibitor, a type of diabetes medicine
- Empagliflozin
a sodium-glucose cotransporter 2 (SGLT2) inhibitor, a prescription medicine that works on sugar handling in the kidneys
- Enalapril
An angiotensin-converting enzyme (ACE) inhibitor
- Furosemide
A loop diuretic, a type of medicine that helps the body get rid of extra fluid through urine
- Hydrochlorothiazide
A thiazide diuretic, a type of medicine often called a 'water pill'
- Lisinopril
an angiotensin converting enzyme (ACE) inhibitor, a type of medicine that helps relax blood vessels to lower blood pressure
- Lithium Carbonate
A mood-stabilizing agent, which the label describes as a medicine used to treat bipolar I disorder
- Risperidone
an atypical antipsychotic medicine
- Spironolactone
An aldosterone antagonist, a type of prescription medicine the FDA classifies this way
- Valsartan
An angiotensin II receptor blocker (ARB), a type of medicine used to treat high blood pressure and certain heart conditions
🔗 Read more from trusted sources
- “Dehydration” on MedlinePlus ↗
US National Library of Medicine
- NCI Dictionary definition ↗
US National Cancer Institute: “dehydration”
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