Body odour is a normal part of life. Contrary to popular belief, sweat in itself does not usually smell. The familiar odour develops when bacteria and fungi that live on the skin break down substances in sweat, particularly secretions from glands in the armpits and groin. In most cases, body odour is harmless and may vary depending on factors such as heat, physical activity, diet and hygiene.
However, a new or persistent change in body odour should not always be dismissed as a hygiene issue, doctors say. In some cases, an unusual odour may be linked to an underlying health condition and may need medical evaluation.
Heat, food and hormones
Several everyday factors can alter body odour. Hot weather and physical activity increase sweating, while tight or synthetic clothing can trap moisture. Garlic, onions, spicy foods, alcohol and certain medicines can also affect body odour.
Hemanath M. J., consultant, internal and family medicine, Apollo Speciality Hospitals, Vanagaram, Chennai, says the apocrine glands in the armpits, groin and scalp contribute more to odour than the eccrine glands, which cover most of the body. Stress can stimulate the apocrine glands and intensify odour.
Hormonal changes can also play a role. Puberty, menstruation and menopause may temporarily alter sweating and body odour. Puberty is one common situations in which changes in body odour are routinely seen. An overactive thyroid, which can cause excessive sweating, may also make odour more noticeable.
A change is more likely to be temporary when there is a clear trigger and the odour settles after the trigger passes. “If somebody develops an odour after eating a particular food, drinking a particular drink, starting a medication or strenuous exercise, or during a period of hormonal change, and it returns to normal after some time, the context helps explain the change,” says Narayanan A., consultant, dermatology, SRM Prime Hospital, Chennai..
Body odour as a health clue
A persistent or unexplained change can sometimes be associated with a skin condition or an underlying medical problem. Skin infections in the armpits, groin or other moist areas can alter odour. These may be accompanied by redness, soreness, itching, peeling or discharge.
“An infection in the groin or axilla (armpit) or excessive growth of bacteria or fungi can alter the odour,” says Dr. Narayanan.
Dr. Hemanath says conditions such as erythrasma and fungal infections can produce a distinct smell, particularly in warm, moist areas. Excessive sweating, or hyperhidrosis, does not itself cause odour but can provide more moisture for bacteria to act on.
Certain metabolic conditions have also been associated with distinctive smells. Uncontrolled diabetes can produce fruity or sweet-smelling breath because of ketone build-up. A rare condition called trimethylaminuria can cause a fish-like odour because the body is unable to break down certain compounds properly.
Odour changes have also been described in advanced kidney and liver disease. But doctors caution against treating these smells as diagnostic tests.
“Some distinctive smells have been described with complications of diabetes, liver disease or kidney disease, but these are clues rather than reliable diagnostic tests,” says Dr. Narayanan. The overall clinical picture, including symptoms, examination and biochemical investigations, is what guides diagnosis.
Need for evaluation
The first step when there is a change in body odour is to look for an obvious trigger. Regular washing, changing sweaty clothes, washing clothes properly and using an antiperspirant can help determine whether the problem responds to routine measures.
But a sudden change in body odour without a clear cause is reason to consult a doctor.The physician would first consider what changed at the same time as the odour. If there is no obvious trigger and the change persists or keeps recurring, a deeper evaluation may be required.
A sudden unexplained increase in sweating, night sweats without an obvious reason, or sweating that interferes with daily activities should also prompt medical attention. Experts list other warning signs such as unexplained weight loss, excessive thirst or urination, fatigue, swelling, fever, night sweats or skin changes. A fruity odour with excessive thirst, frequent urination, nausea, vomiting or confusion requires urgent assessment.
Depending on the symptoms, a doctor may conduct a physical and skin examination and consider tests such as blood glucose and HbA1c, kidney and liver function tests and a thyroid profile. Skin scraping or culture may be considered if an infection is suspected.
Doctors say, body odour should not be used to self-diagnose a disease. Most changes have an everyday explanation, but a smell that is new, persistent, unexplained or accompanied by other symptoms is worth discussing with a doctor
Published – August 28, 2026 10:20 am IST