Bustle magazine recently quoted Dr Yadav in a piece exploring the causes of embarassing rash on bums. Excerpt below:

Have a funny something on your butt? You'd be surprised how common this is and how often people are embarrassed to ask a doctor. Don't be! Here's a short insight into what your rash may be:

Most skin diseases and infections can, involve the skin over the butt. Most commonly, like all hair bearing areas of the skin, the butt can get acne and follicle infection, especially in women who may try hair removal procedures in the area, especially from waxing. This happens when bacteria, usually staphylococcus or 'staph' that live on the skin normally enter via broken skin to cause a pimple like eruption. It can easily be treated with topical antibiotic in about a week. Acne when severe, may extend to the butt region. Pooling of sweat can precipitate prickly heat, fungal infection and other rashes may usually occur here.

However, there are some bumps, that may need a closer look from a doctor:

1. Any bump which is warm, swollen, painful or leaks pus - may be a severe deeper infection that needs oral antibiotics; or even a pilonidal sinus {lower back} or hidradenitis suppurativa (openings leaking pus)
2. Any rash which is itchy, pinkish and spreading - may be a fungal infection or even psoriasis
3. Any swelling that is uncomfortable to sit on - a protrusion may be a haemorrhoid {piles}
4. Any new moles/pigmented patches or a mole which is changing color/shape/size, oozing blood, newly itchy - needs to be assessed. Skin cancer especially melanoma can appear anywhere, including the butt - a regular skin exam helps screen suspicious spots.
5. Rashes from tick bits, bed bug bites etc. may appear in this region and be a clue for your medical diagnosis. Let the doctor know.
6. Allergic reactions to products, especially perfumed ones (which should generally be avoided here)
7. Small watery blisters could be a sign of herpes, which is an STD.

8. Open sores and split skin need medical assistance for healing. They may also be part of a generalized skin disease.

If you've a rash self see your doctor so that they can diagnose and treat you quickly.