Passing very little urine

Category: Urinary & Kidneys · All urinary symptoms

What it can feel like

Passing very little urine means producing much less urine than usual over a day — going many hours without needing the toilet, or passing only small dark amounts. Because urine output is a direct window on kidney function and circulation, a marked fall is taken seriously.

Possible causes

A symptom can have many causes, and most are not serious. The lists below group conditions this symptom can be associated with — common causes first. They are possibilities to discuss with a clinician, not a diagnosis.

Common causes

Reduced output can be associated with not drinking enough, hot weather, vomiting, diarrhoea and fever — situations where the body conserves water appropriately, and output recovers as fluids are replaced.

Other possible causes

Persistently low output can be associated with kidney injury from severe dehydration, sepsis, low blood pressure or kidney-blocking medicines, with obstruction of the urinary tract, and with intrinsic kidney disease.

Red flags — when to seek help promptly

No urine at all for many hours, especially with breathlessness or swelling
Low output with vomiting, severe diarrhoea or inability to drink
Low output with confusion, severe drowsiness or rapid breathing
Low output in a baby, with few wet nappies and sleepiness

What a clinician may do

A clinician will assess circulation and hydration, examine for a full bladder (and scan it), review medicines, and take blood tests for kidney function and salts. A bladder catheter sometimes distinguishes 'not making urine' from 'cannot pass urine' — two very different problems.

Related guides on MedicalVideos.com

Frequently asked questions

How little is too little?

Adults normally produce roughly one to two litres a day. Passing well under half a litre in 24 hours, or nothing for 8–12 hours while awake and drinking, is abnormal and should be assessed the same day — sooner with any of the red-flag features.

What is the difference between not making urine and retention?

In retention the kidneys make urine but the bladder cannot empty — there is usually a palpable, uncomfortable full bladder. In low production the bladder is empty and the problem is the kidneys or circulation. A painless bladder scan tells them apart in minutes.

Related symptoms — Urinary & Kidneys

Being unable to pass urine Blood in the urine Cloudy or strong-smelling urine Difficulty starting to urinate Flank pain Foamy urine

Browse the P section of the A–Z list or return to the Symptoms A–Z hub.

Please note: This page is educational information about a symptom. A symptom alone cannot diagnose any condition, and the causes listed here are possibilities, not a diagnosis. If you are worried about a symptom — especially one that is new, severe, getting worse or not going away — please see your own clinician, who can examine you and arrange tests. In an emergency, call your local emergency number.