Smelly urine
A strong smell from your urine is usually noticed by accident, and then it stays on your mind.
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Medicines commonly prescribed for Smelly urine
For informational purposes only. Always consult a doctor before taking any medication.
Dosage form: ORAL SOLUTION/SUSPENSION, 1 g nitrofurantoin/100 mlActive substance: nitrofurantoinManufacturer: Laboratorios Ern S.A.Prescription requiredDosage form: TABLET, 50 mg NitrofurantoinActive substance: nitrofurantoinManufacturer: Laboratorios Ern S.A.Prescription required
A strong smell from your urine is usually noticed by accident, and then it stays on your mind. On its own it rarely points to illness: most often it comes down to how much you have been drinking and what you have eaten. Sometimes, though, the smell arrives alongside other signs, and then it becomes a useful clue. Below is what changes the smell most often, what you can put right yourself, and when it is better not to delay seeing a doctor.
What urine normally smells like
Freshly passed urine is nearly clear or pale yellow and has only a faint smell. The smell gets stronger when there is little urine and it is concentrated: first thing in the morning, in hot weather, after a long journey without a drink. An ammonia note also appears simply because urine has been standing for a while — in a potty, a bedpan, a nappy — as bacteria break down the urea in it. That is not a disease.
The smell is worth judging on a fresh sample and together with everything else: the colour, how often you pass urine, how you feel in yourself. Taken alone, smell is far too crude a sign to decide anything by.
Dehydration is the commonest cause
The less fluid there is in the body, the more concentrated the urine and the stronger it smells. It darkens at the same time, from deep yellow to the colour of strong tea. This is both the most common cause and the easiest to put right.
The guide is simple: drink enough to pass urine several times through the day, not to feel thirsty, and to see the urine stay pale. Drink more in hot weather, during physical work, and with a fever, diarrhoea or vomiting. There is no need to count litres — watching the colour is simpler and more reliable.
Sugary fizzy drinks, coffee and alcohol do not quench thirst: coffee and alcohol increase how much urine you make, so after them there is less water in the body, not more. If the smell and the dark colour clear within a day or two of drinking normally, there is nothing further to look for.
Food, vitamins and medicines
Some foods change the smell of urine within a few hours of eating them and have no other effect. Asparagus is the classic example: it contains sulphur compounds that the kidneys clear, and they smell sharp. Garlic, onions, coffee, spices and sometimes fish and cabbage do the same. The ability to detect that particular smell differs from person to person and is partly inherited, so one person notices it clearly while someone standing next to them smells nothing at all.
B vitamins, especially B6, turn urine a vivid yellow and give it a characteristic smell; many multivitamins and sports supplements do the same. High doses of B6 taken for a long time can also damage nerves, so they are not something to take for months without medical advice.
Among medicines, some antibiotics, diabetes drugs and certain anti-epileptic medicines change the smell. If the smell started in the first days of a new treatment and there are no other complaints, that medicine is the likely explanation. Do not stop a prescribed treatment because of a smell — it is better to ask the doctor whether it can be expected to settle.
Urinary tract infection: the smell alone is not a diagnosis
An infection is recognised by what happens when you pass urine, not by the smell: burning or pain, frequent and sudden urges, a feeling that the bladder does not empty fully, cloudy urine, blood, pain above the pubic bone. Alongside those signs the smell is part of the picture; by itself it is not.
So a smell cannot be “treated” with an antibiotic, but with those symptoms a urine test does make sense: a basic test shows whether there is inflammation, and a culture shows which bacterium is involved and what will work against it. It is not worth putting off, because a bladder infection can travel up to the kidneys.
A word about home remedies. Cranberry, bicarbonate of soda and herbal teas do not replace treatment. A confirmed infection needs an antibiotic chosen by a doctor; cranberry supplements are discussed only as a way of having fewer episodes in people with repeated cystitis, and bicarbonate used instead of treatment changes little beyond the acidity of the urine and is not harmless for people with heart or kidney problems. Waiting for it to “flush itself out” while there is pain and fever is dangerous.
In an older person the infection looks different
In later life a urinary tract infection often runs without burning and without urgency. Instead there is confusion, unusual drowsiness or, conversely, agitation, weakness, unsteady walking, falls, refusing food; the temperature may be only slightly raised or normal. Relatives put it down to anything from age itself to worsening memory, while the cause sits in the bladder and clears with treatment.
That is why, in an older person, a sudden change in behaviour together with cloudy, strong-smelling urine is a reason to be seen the same day rather than to wait for the “proper” symptoms. The same holds for people with diabetes, after a stroke, and for anyone with a urinary catheter: in them too the infection shows itself faintly.
A sweetish smell and other reasons not to wait
A sweetish smell, or one like acetone or solvent, together with constant thirst, passing urine often, weight loss and no energy, means blood glucose should be checked without delay. That is how diabetes appears when it starts or slips out of control; in a child or teenager the picture develops within days. If deep rapid breathing, tummy pain, vomiting or drowsiness are added to it, an ambulance is needed — in Spain, Italy, Portugal, Poland and Ukraine it is called on the single European number 112.
It is also worth being seen the same day in other situations: fever with shivering and pain in the side or lower back (this suggests a kidney infection); blood in the urine; a strong smell together with genital discharge and itching; a smell that persists for weeks despite drinking normally; a weak stream or a feeling of incomplete emptying in a man. In pregnancy a urinary tract infection is not something to sit out — it is treated, because it can affect the course of the pregnancy, and the medicines are chosen to suit the stage.
Online consultation
Smelly urine is a convenient thing to start discussing remotely. With a doctor you can go through what has changed in your drinking, food and medicines, separate the harmless explanations from an infection, decide which tests to arrange — urine test, culture, blood glucose — and what to do with results you already have. The doctor will say when watching is enough and when an examination in person is needed, and will name the signs that mean waiting is not an option.
This material is for information only and does not replace medical advice.
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