Oil in our skin keeps it hydrated and smooth, and dead cells continuously slough off to keep it looking fresh. When that process goes wrong, pimples can erupt. The appearance of pimple-like bumps on your legs can signal acne or something much less common.

Some general guidelines can help determine whether home care or a trip to the doctor is in order.

It’s important to seek medical attention if a lesion is painful, irritated, or persistent. If not, there are some initial steps you can take:

  • Try cleansers with salicylic acid or glycolic acid.
  • Experiment with benzoyl peroxide, a common and effective spot treatment.
  • Look for moisturizers or sunscreens that are oil-free or “noncomedogenic.”
  • Tight clothes can irritate your skin. Change clothes with sweat or oil as soon as possible.
  • Monitor sun exposure. Sun can help with superficial acne, but it also can encourage the production of sebum and lesions. Always use a sunscreen.
  • Try a warm compress to loosen and soften any acne lesions.

Lesions that aren’t susceptible to the above steps may not be acne and should be seen by a doctor. If the doctor diagnoses acne, it will fall into one of four categories: mild, moderate, moderate to severe, and severe. Several treatments are available:

Topicals derived from vitamin A. These are both over-the-counter and prescription. Tretinoin is the best known of the prescription options, but your doctor may suggest other versions.

Benzoyl peroxide. A variety of compounds are available over the counter. Your doctor may recommend a compound that’s available only with a prescription. Treatment of moderate acne usually starts with a 5 percent solution.

Antibiotics. Your doctor may recommend minocycline and doxycycline to treat bacteria associated with acne. Antibiotic therapy is less popular than it was in the past due to a growing concern about antibiotic resistance.

Systemic drugs derived from vitamin A. Tretinoin by mouth is reserved for severe cases of cystic acne. It is effective, but linked to serious side effects, including the risk of birth defects.

The various treatments for acne can have complicated and serious interactions. Antibiotics can decrease the effectiveness of female oral contraceptives. Sun sensitivity is more likely with some antibiotics, vitamin A compounds, and nonsteroidal anti-inflammatory drugs (NSAIDs).

Acne lesions, particularly severe acne, can be painful. Appropriate and prompt treatment may begin with nonsteroidal medications such as ibuprofen or naproxen. Your doctor can recommend a painkiller to ease the discomfort. They may recommend prescription drugs if these are not effective.

Don’t squeeze pimples. It might force an infection deeper into the skin and cause a scar to develop.

Acne is a broad term that describes a variety of conditions that can appear on the skin. It arises mostly on the face and back, but can appear almost anywhere you have an oil-producing gland, including the legs.

There are several things that can lead to acne on the legs. These include:

  • unbreathable fabrics
  • tight pants that rub against the legs
  • irritating laundry detergents
  • sweating on the legs
  • contact with unclean gym equipment
  • red bumps from shaving that have become infected
  • follicular inflammation (inflamed hair follicles)

A closed pore clogged with oil is called a whitehead. Blackheads form when that oil is exposed to air and combines with oxygen. Raised red bumps (papules) with pus are called pimples.

The sloughed-off skin and oil are often contained in a sac under the skin. The sac under the skin can break, become irritated, or even infected, and form cysts and nodules.

Acne is very common. About 40 to 50 million Americans have it at any given time.

Less common conditions can be confused with acne. They include:

  • epidermal cysts or deep milia, little bumps of trapped skin cells
  • osteoma cutis, caused by bone cells that arise under the skin
  • adnexal neoplasms, relatively rare and usually benign skin growths
  • folliculitis, an inflammation or disease of the hair follicle
  • keratosis pilaris, characterized by small bumps that can appear anywhere on the body, but especially the extremities (it’s possible that people with keratosis pilaris are less likely than average to have acne)
  • flat warts, often resolve by themselves, but can be treated with good hygiene at home

One study looked back at the records of patient diagnosed with “tender, cutaneous nodules” or small sores, on the leg. When it was possible to make a diagnosis, the most common (84.4 percent) was inflammation, the body’s reaction to a foreign substance. Infections and tumors were about the same, at 5.8 and 6.5 percent. About two-thirds of the patients in the study were women.

Skin can change dramatically during pregnancy. Bouts of acne or other conditions are not uncommon. However, unusual or troubling changes should be seen by a doctor as soon as possible.

Doctors have some general advice on preventing acne:

Eat a healthy diet. That’s always a good advice, but medical professionals tend to downplay the role of diet in preventing or treating pimples.

Hygiene. Keep your body clear of excess oil and grime that can clog pores, and do it correctly. Don’t use conventional soap. Choose a cleanser that’s close to the pH of your skin. Scrubbing can irritate your skin.

Gently wash and pat dry instead. If meticulous hygiene doesn’t clear up the acne, remember that the condition begins below the surface of the skin and may need more focused treatment.

Monitor sun exposure. Sun can help with superficial acne, but it also can encourage the production of sebum and lesions. Always use a sunscreen.

Acne treatments can take anywhere from several weeks to several months to produce noticeable results. Researchers recently looked at what treatments were most likely to maintain successful acne therapy. The treatment regimens most likely to help clear skin and keep further breakouts at bay were topical and systemic drugs followed by topical treatments.