Reference
Drinking, when every sip has to come back out.
Anyone who catheterises knows the temptation: drink less, and you will need the catheter less often. It is the most understandable mistake with ISC — and the most harmful. This page explains why, and what works instead.
Who these guidelines are not for: if you have a fluid limit set by your doctor because of a heart or kidney condition, that limit always comes first. This page is for people whose fluid intake is constrained only by the bladder, not by another condition.
Why cutting back backfires
Drinking little makes the urine concentrated. Concentrated urine irritates the bladder lining, smells stronger, and germs multiply in it more easily because the bladder is flushed less often — so the infection risk rises through the very measure that was meant to make life easier. Added to that: a higher risk of urinary stones, constipation (already an issue with a neurogenic bowel), and for many people circulation problems, because blood pressure after a spinal cord injury is often low to begin with.
The maths does not work out either: what is saved is usually a single catheterisation a day — bought with a risk that in the worst case means antibiotics, stone treatment or a feverish infection.
Orientation
How much — and above all, when.
The total is only half the truth. Just as important is how it is spread across the day — that is what decides whether the night stays quiet.
| Measure | Usual range | What matters |
|---|---|---|
| Fluid intake per day | 1.5–2 l | More in heat, during sport or with fever. What applies to you is set by your care team |
| Distribution | evenly, in portions | Many small portions fill the bladder predictably; a litre at once breaks any interval |
| In the evening | ease off ~2 h before sleep | Easing off means shifting, not cutting — the total stays, it moves into the day |
| Coffee, tea, alcohol | count too | They are diuretic and make volumes briefly harder to plan — plan them in rather than ban them |
| Volume per emptying | under 400–500 ml | The control measure: if it is exceeded despite normal fluid intake, the interval needs to be shorter — more on the ISC page |
The rule of thumb behind it: not less fluid, but smarter timing. Placing your intake in the morning and afternoon means predictable catheterisations during the day and an undisturbed night — without taking anything away from bladder or kidneys.
The balance: seeing intake and output together
Only when you lay fluid intake and urine volumes side by side do the real questions become answerable. Does roughly as much come out as goes in? Is the urine dark in the morning because the evening was eased off — or all day, because the total is too low? Is the large evening volume down to the drink at 9 pm?
A few days of balance show more than weeks of guessing. And they are the basis on which drinking times and catheter interval can be adjusted together — instead of turning one dial and wondering about the other.
Why keeping notes helps
On paper, the bladder diary template works for this — it records fluid intake alongside urine volumes. More convenient is the Bladder & Bowel Manager: fluid tracking is optional (off by default), volumes go into the log in two seconds via quick-select, and the statistics show the intake/output balance by themselves. Everything stays on your device.