Day three of a cold. You’re on the couch under a blanket, a mug of tea going cold on the table, and someone who loves you texts: “drink lots of fluids!” Nobody ever says how much. Nobody mentions where the advice comes from, either.
So we looked it up. Short version: water is not cold medicine, but it does one job for real — keeping a sick body from sliding into dehydration on top of everything else. Here’s why that distinction matters, what to drink for which symptom, and where sports drinks and oral rehydration solutions actually fit.
At a glance
- “Drink plenty of fluids” is half true — forcing extra fluids has never been tested in a trial. The real job is preventing dehydration.
- Fever raises what you lose through skin and breath. Small, steady sips beat heroic chugging, thirsty or not.
- Kids and older adults dehydrate fast. If fluids won’t stay down or urine nearly stops, that’s a doctor call, not a hydration question.
We went looking for the evidence behind “plenty of fluids”
It may be the most-prescribed advice in medicine, and for a very long time nobody asked it for receipts. When someone finally did — a systematic review in the BMJ, later repeated as a Cochrane review — they found not a single randomized trial testing whether extra fluids help a respiratory infection. Advice that old, never actually put on trial.
That doesn’t make water useless. It changes the job description. Fever raises what leaves through skin and breath while a flattened appetite cuts what comes in, and left alone that gap turns into dehydration — which makes every part of being sick feel heavier. The honest version of the advice: fluids won’t flush the virus out, they keep a second problem from stacking onto the first. Sip steadily. Don’t force it down by the pint.
What to drink, symptom by symptom
One study is worth knowing before the table. Researchers gave people with colds a hot drink and measured their nasal airflow — objectively, nothing opened up. Subjectively, runny nose, cough, sore throat, and chills all eased, and the same drink at room temperature did less. Sometimes “it just feels better” is the honest mechanism. That still counts; comfort is what keeps you drinking.
| Symptom | What tends to go down well | What to skip for now |
|---|---|---|
| Fever | Water or weak tea in small, frequent sips; broth when appetite is gone | Alcohol, and “catching up” with one giant bottle |
| Sore throat | Warm tea with honey — or ice-cold water, if that’s what your throat prefers | Anything too hot to swallow comfortably |
| Congestion | Hot drinks. Chicken soup earns its reputation: steam, salt, and fluid in one bowl | Nothing, really — but no drink “clears” sinuses either |
| Stomach bug | Oral rehydration solution, or plain water one sip at a time | Caffeine, soda, very sugary juice; pause milk if it makes diarrhea worse |
Sports drinks, oral rehydration, and when to stop self-treating
When appetite is gone and plain water won’t go down, a sports drink can bridge the gap — an easy flavor that keeps the total from collapsing. Just know what it is: closer to a soft drink with electrolytes sprinkled in than to medicine. The sports drinks guide has the full picture.
Oral rehydration solution is a different tool entirely — sodium and glucose in a ratio engineered for absorption, built for when vomiting or diarrhea drains water and electrolytes together. For an ordinary cold where you’re still eating and drinking, it’s overkill. Water, tea, and soup cover it.
On a sick day the goal isn’t a full ring. If you track with WOOMOOL, ignore the target and watch one thing: how long since the last sip. Keeping that under a couple of hours is enough.
Frequently asked questions
- How much water should I drink when I’m sick?
- There’s no evidence-backed “sick-day dose.” Keep your normal total — the calculator gives you a weight-based starting point — and add a little on top when you’re running a fever. Pale urine and a mouth that isn’t dry are more honest gauges than any number.
- Is hot water better than cold water for a cold?
- For hydration they’re identical. Hot drinks relieved cold symptoms in a small study — subjectively, without measurably opening the nose — so if warmth comforts you, use it. If your throat wants cold, cold is right too.
- Do sports drinks help when you’re sick?
- As fluid, yes — and the easy taste helps when nothing else goes down. As medicine, no. With diarrhea, their sugar can make things worse; that’s the moment for an oral rehydration solution instead, and a doctor if it doesn’t settle.