10 Causes of Body Odour – When Is It a Medical Problem?

Reviewed by Dr Lauren Holland • Marylebone Diagnostic Centre
Results within 24 – 42 hours. Westminster residents receive 20% off.

Body odour is normal, but a sudden change in smell or unusually strong odour can feel worrying. Many patients in London notice odour after showering, stronger armpit smell at the end of the day, or a new scent they have not experienced before. While sweat itself has no smell, bacteria, hormones, diet, stress and underlying medical conditions can all change how the body smells.

Clinically, we often see body odour linked to metabolic changes, vitamin deficiency, thyroid imbalance, diabetes risk, liver stress or hormonal shifts. Blood testing is one of the fastest ways to understand whether odour is simply environmental or a sign of an internal imbalance. This guide explains the main causes and when to seek testing at Marylebone Diagnostic Centre.

Hormonal Changes

Hormone shifts can change sweat production and bacterial activity.

Common signs:

• stronger odour before a period
• smell changes in perimenopause
• teenage hormonal changes
• odour after starting or stopping hormonal contraception

Hormonal imbalance can also influence the type of bacteria living on the skin.

Recommended MDC tests:

• Thyroid Panel
• Sex Hormone Profile (if clinically relevant)
• Wellness Profile

Stress and Cortisol Spikes

Stress sweat smells stronger because it comes from apocrine glands. This sweat is rich in proteins, which bacteria break down into strong-smelling compounds.

Triggers:

• work pressure
• lack of sleep
• anxiety

Stress-driven odour may appear even after showering.

Recommended MDC tests:

• Wellness Profile
• Vitamin & Mineral Profile

Diet and Gut Bacteria

Foods that may worsen odour include:

• onions
• garlic
• alcohol
• spicy food
• high-sugar diets

Poor digestion or gut imbalance can also produce unusual smells.

Recommended MDC tests:

• Vitamin B12
• Vitamin D
• Full Wellness Profile

Diabetes & Blood Sugar Imbalance

High blood sugar changes sweat composition. In some cases, a sweet or fruity smell may occur.

Symptoms linked:

• thirst
• fatigue
• frequent urination
• dizziness

This is one of the most important medical causes to rule out.

Recommended MDC test:

• HbA1c (Diabetes Check)

Thyroid Imbalance

The thyroid controls metabolism. When underactive or overactive, sweat production and body temperature shift.

Signs:

• dry skin with odour changes
• sweating more or less
• feeling hot or cold
• weight changes

Recommended MDC test:

• Thyroid Panel

Vitamin & Mineral Deficiencies

Low vitamin D, magnesium and zinc affect sweat gland function and bacterial balance. Many people in London develop deficiencies during winter.

Possible symptoms:

• fatigue
• weak immunity
• muscle aches
• new odours

Recommended MDC test:

• Vitamin & Mineral Profile

Liver Stress

The liver removes toxins. When stressed, waste products may build up and change how sweat smells.

Causes:

• alcohol
• medication
• fatty liver
• infection

Patients often describe a strong or sour smell.

Recommended MDC tests:

• Liver Function
• Wellness Profile

Kidney Stress

Kidneys remove waste from the blood. When they struggle, toxins can leave the body through sweat, causing strong or ammonia-like odour.

Symptoms:

• swelling
• fatigue
• changes in urination

Recommended MDC tests:

• Kidney Function
• Wellness Profile

Excess Bacteria on the Skin

Even with good hygiene, some people develop higher bacterial activity due to:

• tight clothing
• synthetic fabrics
• poor ventilation
• shaving irritation

This often causes persistent armpit odour.

Medical tests are not always required unless symptoms overlap with fatigue or systemic changes.

Trimethylaminuria (Rare)

(“Fish odour syndrome”)

A rare condition where the body cannot break down trimethylamine (TMA). It causes a strong, fish-like smell.

This requires specialist advice, but general screening often helps rule out other causes first.

When Is Body Odour a Medical Concern?

Seek testing if you experience:

• sudden change in odour
• persistent smell after showering
• odour with fatigue
• odour with dizziness
• fruity smell (possible diabetes)
• ammonia-like smell (kidney related)
• strong odour with weight changes
• odour with excessive sweating
• odour with yellow skin or eye changes

These may indicate metabolic or hormonal imbalance.

Best MDC Tests for Unexplained Body Odour

Wellness Profile

Most complete. Covers:

• liver
• kidney
• blood sugar
• thyroid
• vitamins
• minerals
• FBC
• CRP

HbA1c

Essential for diabetes screening.

Thyroid Profile

Important if odour changes with weight, mood or energy.

Vitamin & Mineral Profile

Useful when diet, low energy and muscle symptoms are present.

Liver Function Test

For sour, bitter or unusual body smells.

Kidney Function Test

For ammonia-like smells.

Symptom–Test Matching Table

Clinical Insight

“When body odour appears despite good hygiene, we often find metabolic or hormonal changes. A simple blood test can identify the cause and provide reassurance.”
– Dr Lauren Holland

FAQs

Book Your Body Odour Investigation at Marylebone Diagnostic Centre

Marylebone Diagnostic Centre
73 Baker Street, London W1U 6RD
Tel: +44 7495 970109
Open Monday–Saturday, 08:00–16:00

Fast, private and confidential testing.
Results within 24–42 hours.
Westminster residents receive 20% off.

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Read More

• NHS – Causes of Body Odour
• NHS – Diabetes Symptoms
• British Liver Trust – Liver Disease Symptoms
• Kidney Care UK – Kidney Disease Symptoms