Excessive sweating in one armpit

Compare the two sides: note when it began, whether the skin is red or tender, and whether sweating happens during heat, exercise, stress, or sleep. A new one-sided pattern deserves attention because friction, shaving, a blocked follicle, infection, or a nearby skin problem may be contributing. Sweating can also occur with conditions such as hyperthyroidism, hypoglycaemia, heat exhaustion, or obstructive sleep apnoea. See the broader overview of Excessive Sweating for context.

Keep the area cool and dry, wear breathable clothing, and stop any recently introduced fragranced product if it stings or irritates. Do not apply strong antiperspirants to broken skin. Record triggers and medicines, including supplements, before an appointment. A clinician can examine the skin, review possible causes, and discuss options such as Botox For Sweating, Iontophoresis, or Microwave Sweat Gland Treatment when appropriate for the location.

Arrange medical assessment if the change is persistent, worsening, starts suddenly, or comes with a lump, pain, rash, odour, fever, weight change, palpitations, dizziness, or night sweats. Seek urgent help for confusion, fainting, severe weakness, chest discomfort, or trouble breathing, especially after heat exposure or with low-blood-sugar symptoms.

Could a skin irritation, medicine, or medical condition explain the difference? Should the underarm skin or nearby lymph nodes be examined? Which treatment fits the affected area, and what skin reactions should prompt a call?