Urinary tract infections (UTIs) are common and affect many people across the UK, particularly women and older adults. Most cases cause symptoms such as a frequent urge to urinate, burning when passing urine, or discomfort in the lower abdomen. 

However, some people also notice unexpected symptoms, such as tiredness or even weakness in their legs. This connection can be worrying, especially if the weakness appears suddenly. 

What are urinary tract infections?

A urinary tract infection happens when bacteria enter the urinary system and begin to multiply. The infection can affect the bladder, urethra, ureters, or kidneys. In most cases, the bladder is involved, which is known as cystitis.

Typical symptoms include:

• Strong urge to urinate
• Cloudy or strong-smelling urine
• Pain in the lower abdomen
• General feeling of being unwell.

While mild infections often improve with treatment, a severe or untreated UTI can spread to other parts of the body. This spread can affect overall health, leading to symptoms beyond the urinary system.

Why you might feel weak during a UTI

When your body fights an infection, it uses energy to activate the immune system. This process can make you feel unusually tired or weak. The infection itself can cause inflammation, pain, and fever, all of which contribute to fatigue.

Dehydration can also play a part. Many people drink less because urinating becomes painful or frequent, but this lack of fluids can make muscles feel heavy and weak. The discomfort from a UTI might also affect your sleep, which adds to general exhaustion.

Can a urinary tract infection directly cause leg weakness?

A mild UTI usually does not directly affect the legs. However, in some situations, the infection might lead to weakness or discomfort in the lower limbs. This can happen for a few reasons:

1. The infection has spread beyond the bladder

If a UTI is left untreated, bacteria might travel to the kidneys, causing a more serious infection known as pyelonephritis. 

When this happens, the body produces a stronger immune response, leading to high fever, chills, and fatigue. This can make the legs feel weak or heavy as your body uses energy to fight the infection.

Related guide: How Long Does It Take For A UTI To Turn Into A Kidney Infection?

2. The nervous system is involved

In rare cases, bacteria from a severe UTI can spread into the bloodstream, causing a condition called sepsis. This can affect the entire body, including the nervous system and muscles. 

When nerves or muscles are affected, you might feel weakness or tingling in your legs. Sepsis is a medical emergency that needs immediate hospital treatment.

3. Older adults or those with existing conditions

Older adults, particularly those with diabetes or nerve-related problems, might experience weakness in their legs during a UTI. 

This happens because their body’s response to infection is different, and the symptoms are sometimes less typical. Instead of pain or burning during urination, weakness or confusion might appear first.

Recognising warning signs that need urgent care

While mild weakness can be part of feeling generally unwell, certain signs mean you should seek medical help straight away. These include:

• Severe back or side pain
• High fever or chills
• Feeling dizzy, confused, or faint
• Difficulty moving your legs or sudden muscle weakness
• Persistent vomiting or inability to drink fluids

These symptoms might suggest that the infection has spread or that sepsis is developing. Early treatment can prevent serious complications.

How leg weakness and urinary issues can be connected through nerves

Your bladder and legs share some nerve pathways in the lower spine. Conditions that affect these nerves, such as spinal infections or inflammation, can cause both urinary symptoms and leg weakness. 

In rare cases, a severe bladder infection might irritate or press on these nerves, especially if swelling occurs nearby.

If you notice leg weakness together with bladder control problems, such as difficulty urinating or incontinence, you should contact a doctor immediately. 

This combination might indicate a neurological problem like cauda equina syndrome, which needs urgent attention.

Preventing urinary tract infections and related complications

While most UTIs are mild and respond well to antibiotics, prevention remains important. Here are a few practical ways to reduce the risk of infection and its complications:

• Drink plenty of water to help flush out bacteria.
• Empty your bladder fully when you urinate.
• Maintain good hygiene, especially after using the toilet.
• Avoid holding in urine for long periods.
• For women, wiping from front to back helps prevent bacteria from spreading.

If you’re prone to recurring infections, your doctor might suggest urine tests or imaging to identify any underlying cause. 

Regular check-ups can also help detect any nerve or structural issues that might make infections more frequent.

What treatment options are available?

Treatment for a UTI depends on its severity. Most infections clear with antibiotics prescribed by a healthcare professional. Drinking more fluids, resting, and taking pain relief for discomfort can also help recovery.

If the infection spreads to the kidneys or bloodstream, hospital treatment might be needed. In these cases, antibiotics are usually given by vein, and close monitoring helps prevent complications such as sepsis.

If you’re experiencing ongoing weakness or fatigue even after the infection clears, it’s worth returning to your doctor for further tests. 

Sometimes, another condition, such as nerve inflammation or muscle fatigue, might be contributing.

Let your body rest

A urinary tract infection might cause weakness in your legs, particularly if it’s severe or spreads beyond the bladder. The weakness often comes from the body’s effort to fight infection, dehydration, or nerve irritation. 

Most cases improve with proper treatment and rest, but you should always seek medical advice if symptoms worsen or new problems appear.

Always consult a healthcare professional if you experience unusual leg weakness, severe pain, or fever during a UTI, as these might signal a more serious condition that needs immediate attention.