Strong smelling urine: What Causes Urine Smell and What Does it Mean?

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, leaving you wondering ‘why does my urine smell bad?’. There can be several reasons for this.

The different urine smells

In the past, urine could be used to diagnose diseases and provide clues to identify various medical conditions affecting people. Today, along with urine colour, the smell of urine can be used to indicate either good health or illness. Urine smell can vary depending on various factors and can be quite pungent. Some common urine smells include, sweet smelling urine, urine that smells like fish, ammonia or even alcohol. 

What causes strong smelling urine in adults? Possible urine smell causes

There are various causes of smelly urine, and it can be quite noticeable if the urine smells unpleasant or more intense than usual. Some examples of what could cause a strong smell in urine include: 

1. Food 

The smell of urine is strongly linked to what we eat. The relationship between asparagus and smelly urine is well known, as it gives 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 

  • 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.  

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 

Strong smelling urine that is dark and cloudy may be due to a urinary tract infection or Asymptomatic Bacteriuria (see below). 

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. Urinary or bladder infection occurs more often in women because the urethra is shorter and closer to the anus. This means that smelly urine in women can often be caused by infections such as this. 

In addition to bacteria, viruses or fungi can also 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 

As mentioned above, bacteria can populate the urinary tract. These 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. 

Smelly Urine in Women

Aside from the main common causes of urine smell mentioned above, women may also experiences changes due to: 

  • Pregnancy 

  • Diet 

  • Bacterial vaginosis 

  • Ovulation 

  • Medications (such as birth control) 

  • Hormonal changes 

  • Sexually transmitted infections 

Smelly Urine in Men

Aside from the above, some additional causes of smelly urine in men include: 

  • Diet 

  • Medications or supplements 

  • Sexually transmitted infections 

  • Hormonal changes 

  • Medications 

  • UTI (This cause is less common in men but still important to be aware of) 

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 and resulting strong smelling urine

  • 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  

  • 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 incontinence 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.