Strong smelling urine: causes of smelly urine and what it can indicate

The smell of urine is usually rather neutral if you drink enough water (usually about one and a half to two litres a day) and empty the bladder at regular intervals. But sometimes even fresh urine can have a strong smell, and there can be several reasons for this.

The different urine smells

In the past, urine was used to diagnose diseases and provide clues as to whether something was wrong in the body. Today, along with the colour and symptoms, the smell in urine can help indicate either good health or illness. The smell can be described in many different ways; from , sweet smelling urine, to  urine that  smells like fish, ammonia or alcohol.

Why does my pee smell? Possible urine smell causes

There could be various reasons why the urine smells unpleasant and more intense. Below are some examples of what could cause a strong smell in urine.

1. Food

The smell of  urine is strongly linked to what we eat. Asparagus is perhaps the most known food for giving urine a distinctly strong odour, due to the sulphur-containing chemicals produced when it is digested. 

Spicy food, such as curries, can also give urine a stronger smell. Coffee, garlic and brussel sprouts will all give urine a more distinctive odour, as they are broken down by the body when digested. 

2. Medication

Medicines like penicillin can also affect the way urine smells, as some ingredients that go into this antibiotic are derived from mould, which can give urine a yeast-like smell. However, this is all completely harmless and should not persist once the course of medication is over.

Vitamin B supplements may also contribute to strong smelling urine, which may smell slightly musty. However this is not a cause for concern.

3. Dehydration

When you don’t drink enough water, urine becomes more concentrated – this is reflected in its colour and smell. If urine is dark in colour with a strong smell, this likely indicates dehydration. 

Highly concentrated urine, caused by low fluid intake, is often strong-smelling.  When urine is too concentrated, it also irritates the bladder lining. This can cause urge symptoms, which are characterized by a frequent need to go to the toilet

Conditions that can lead to dehydration include fever, kidney disease, diarrhoea or vomiting. Anyone can become dehydrated, but some people are more at risk, e.g. small children, the elderly or people with a chronic disease or illness. If you suspect dehydration, in yourself or in others, it’s important to act. Always make sure you, or those you care for, get enough fluids. 
Strong smelling urine that is dark and cloudy may be due to a urinary tract infection or Asymptomatic Bacteriuria (see below).

4. Bacteria

Urine is not sterile, as it was once commonly thought, and the urinary tract has its own community of bacteria, called a ‘microflora’. This means that most people have small amounts of bacteria in their urine.  This is quite normal and doesn’t cause any discomfort. Research is ongoing to find out the composition of this microflora, whether it is stable or not and whether it can help prevent infections caused by other unwanted bacteria.

5. Urinary Tract Infection

Sometimes, unwanted bacteria can enter the urinary tract and cause an infection – known as urinary tract infection or, when it affects the bladder, cystitis. This is often caused by the E.coli bacteria that occur naturally in the intestine, and which sometimes get into the urethra and travel up the urinary tract. In women, a urinary or bladder infection occurs more often because the urethra is shorter and closer to the anus. In addition to bacteria, viruses or fungi can trigger an infection. The invading bacteria thrive in urine and multiply quickly and cause an infection, which can result in strong smelling urine.

Symptoms of a urinary tract infection or cystitis can include:

6. Asymptomatic Bacteriuria

It is also possible that large numbers of bacteria can populate the urinary tract. The bacteria are usually of different types and not known to be harmful. This means they can be present without causing any problems, apart from making the urine appear cloudy and sometimes smell unpleasant. This condition is known as Asymptomatic Bacteriuria (ASB). These bacteria are more common in older adults , in women and in people with diabetes or catheters. This condition  should not be treated with antibiotics. This is because if the balance of the microflora is altered, antibiotic treatment may allow other bacteria to flourish that are more difficult to deal with.

7. Diabetes

For people with diabetes and a blood glucose level that is too high, the kidneys pass excess sugar out through the urine. This can cause sweet smelling urine . Other symptoms of high blood sugar are feeling very thirsty and urinating frequently. If you have symptoms of high blood sugar, you should contact your doctor.

Strong urine smell: when to see a doctor

If urine smells bad, it doesn’t necessarily mean that something is wrong. However, if the smell in urine lasts for a long time and cannot be traced back to certain foods or medicines, and you are worried about symptoms, the cause should be investigated. If the colour of the urine has changed, if there is a pain when urinating or even blood in the urine, then a more thorough diagnosis is required. If you are concerned, you should contact your doctor.
If there is an unpleasant smell from the genitals, this could for example be caused by a bacterial imbalance. Reasons for this could be excessive hygiene, antibiotic treatment or using harsh soaps.

How to reduce the risk of a urinary tract infection

  • Be extra attentive if there is any previous history of a urinary tract infection, or if a person has been assessed to be at risk.

  • Drink enough fluids to stay properly hydrated.

  • Try to avoid prolonged skin exposure to urine (i.e. wet incontinence products containing a lot of urine).

  • Use products with materials that keep the skin dry (e.g. by wicking away the urine into the product core to keep it away from the skin).

  • Employ toileting routines that facilitate a complete bladder and bowel emptying, since residual urine could be a risk of urinary tract infection. 

  • Wipe from front to back after a bowel movement, to avoid transferring bowel bacteria to the urinary tract.

  • Remove products soiled with faeces immediately – from front to back. 

  • Avoid harsh soap sensitive areas around the genitals, as it can cause imbalance and irritation. Always choose skincare and cleansing products with a low pH (pH 4.0-6.0). This is especially important for the skin of an older adult and for sensitive skin. 

  • Use TENA wash cream or wet wash gloves to clean fragile skin, and TENA barrier cream for extra skin protection. 

  • Dry the skin gently after cleaning and before putting on a new product, since bacteria grow better in moist areas. Expose to air if possible.

Asking 'why does my pee smell?' can provide important information

To sum it up: When the smell of urine changes, it can be an important indicator of many things. The cause can be harmless, such as  something you’ve eaten. But it could also be dehydration or infection that causes the urine to have an unusual smell. 

An attentive nose, together with a keen eye for other symptoms, can provide valuable hints – and if necessary, lead to a request for a medical diagnosis. There are also many helpful TENA incontinence products available to help keep the skin dry and prevent urine odour, as well as TENA cleansing products to clean, moisturise and protect the sensitive skin down below.