I've noticed a pretty big red pimple under my left breast. It's turned dark now, and I've got a few smaller red pimples nearby. I'm really scared this might be something serious like breast cancer. I started exercising almost every day, but I'm not wearing a sports bra, just a regular tight one. Could the sweat and friction from that be causing these to show up under just one breast?

Dr Mubarak Parveez B

General Practitioner

• MBBS
• 2+ Yrs

Consult Now

Don't worry, I'm here to help you figure out what might be going on.

The symptoms you're describing - a red pimple under your left breast that's turned dark, with other small red pimples nearby - are unlikely to be breast cancer. Breast cancer typically presents as a lump or thickening in the breast tissue, not as pimples or skin lesions [1).

That being said, it's always a good idea to get any new or changing skin symptoms checked out by a doctor. They can take a closer look and provide a proper diagnosis.

As for the possible causes, sweat and friction from exercising and wearing a tight bra could definitely contribute to skin irritation and pimples in that area. This is especially likely if you're not wearing a sports bra that fits well and allows for good airflow

Answered 04/07/2025