What should you know about change in underarm smell?

A new underarm smell is usually caused by changes in moisture, skin bacteria, irritation, products, or sweating. The odour develops when skin bacteria break down substances in sweat, so a change does not automatically point to a serious disease. Notice when it began and whether it follows exercise, stress, a new product, or a change in washing or clothing.

More sweating can leave the underarm warm and damp, allowing odour-producing bacteria to thrive. A new deodorant may irritate the skin or mask rather than remove the smell. Shaving, friction, eczema, or an infection can disturb the skin barrier. Hormonal changes, diet, and medicines may also affect odour, while smell by itself cannot diagnose the underlying reason.

Clean the area with a mild product, rinse well, and pat dry. Wear clean, breathable clothing and change it after sweating. Stop any newly introduced fragranced product if the skin stings or becomes red. Do not apply deodorant to cuts or inflamed skin. If sweating is difficult to control, ask about prescription antiperspirant or treatment with botulinum toxin for hyperhidrosis.

Book an appointment when the smell lasts despite simple measures, keeps recurring, or is accompanied by redness, scaling, itching, tenderness, discharge, sores, a lump, fever, or a marked change in sweating. Get urgent help for breathing trouble, throat or tongue swelling, faintness, or rapidly worsening symptoms. The clinician may inspect the skin and ask about products, medicines, and general health.

Does my skin show irritation or infection? Could my medicines or sweating pattern contribute? Which products are least likely to irritate me? When should I seek urgent help?