Skin boils are infections caused by bacteria or fungi. They commonly develop as a lump around a hair follicle or oil gland.

Looking at pictures of boils and understanding the conditions that cause them can help you recognize them if they appear on your body and know what to do for treatment.

This article explains boil symptoms, how boils differ from other similar skin conditions, and conditions that result in boils.

Boil Symptoms

An infection of Staphylococcus bacteria is often the cause of skin boils, but boils may develop from other infectious agents, like group A Streptococcus. Skin boils can have a pinkish, red, or whitish-yellow color with symptoms that include:

• Swelling
• Oozing of pus or clear fluid
• Crusting
• Pain

Boil vs. Pimple

Skin boils and pimples can look similar, but there are differences. For example, unlike boils, an infection is not the cause of pimples. Instead, pimples are usually the main symptom of acne—a common skin condition that occurs from blocked pores.

Due to this blockage, pimples, blackheads, and whiteheads may form a bump on the skin. Sometimes, with acne, bacteria can infect clogged pores, leading to redness and inflammation. This type of acne is known as inflammatory acne.

Boil vs. Cyst

Boils also differ from cysts, which are fluid-filled sacs that are typically non-infectious and non-contagious. However, cysts can become infected if bacteria gets in broken skin. In addition, boils usually multiply and can be painful, while cysts typically grow slowly and aren’t painful.

MRSA Blister

A blister caused by methicillin-resistant Staphylococcus aureus (MRSA) infection is also called a staph infection. But even though it’s common for MRSA to show up as blisters or boils, not all blisters or boils are from MRSA.

Other forms of MRSA and group A Streptococcus bacteria cause skin infections that look very similar.

Symptoms

MRSA can colonize (live) on the skin and cause no harm. However, when you have a cut or scrape, the bacterium can enter the body and cause infection. When this occurs, symptoms may include:

• Pain
• Swelling
• Redness
• Fever

MRSA can spread by touching someone’s skin colonized with MRSA or touching contaminated surfaces.

MRSA blisters commonly form on areas covered by hair, such as the back of the neck, groin, buttocks, armpit, and beard areas.

Treatment

Due to this bacterium’s resistance to many standard antibiotics, treating it requires specific types of medication and dosages. Usually, treatment involves a seven to 10-day course of oral antibiotics such as:

• Trimethoprim-sulfamethoxazole
• Clindamycin
• Minocycline
• Linezolid
• Doxycycline

Cystic Acne

Cystic acne is the most severe type of acne. It causes acne cysts that form deep under the skin.

It occurs due to the pores in the skin becoming clogged with excess sebum (an oily substance found in glands) and dead skin cells. When bacteria infect these clogged pores, the immune system reacts to fight the threat. This reaction causes deep swelling in the skin’s middle layer (the dermis).

Symptoms

An acne cyst is usually red and may have a whitish-yellow head. A cyst can be crusty, painful, or tender to touch, and either large or small in size.

Since the face has an abundance of oil glands, acne cysts tend to appear there. However, they can also appear on the back, butt, chest, neck, shoulders, and upper arms.

Treatment

Treating cystic acne typically includes taking oral antibiotics and applying certain topical gels or creams (often prescription-strength) to the affected area. Some treatments include the use of:

• Azelaic acid
• Benzoyl peroxide
• Retinoids
• Salicylic acid

Impetigo

Impetigo is a bacterial skin infection that is pretty common in kids (in fact, some incorrectly pronounce it infantigo). It comes from either Staphylococcus or Streptococcus bacteria.

Impetigo is highly contagious and can spread by contacting an infected person’s sores, mucus, or nasal discharge. It can also spread by sharing towels or clothing with an infected person.

Symptoms

Symptoms of impetigo typically occur within three days after infection and can include:

• Skin lesions on the lips, nose, arms, and legs
• Pus-filled blisters that can easily burst
• Swollen lymph nodes around the infected area
• Reddish skin with blisters that contain tan or yellowish fluid
• Rash

Treatment

Impetigo is treatable, doesn’t cause a fever, and healthcare providers will most likely be able to identify it just by looking at it. However, if they aren’t sure, they may take a biopsy of the affected skin to see if it’s impetigo or not.

Treating impetigo typically involves applying prescribed topical antibiotics such as mupirocin or taking oral antibiotics such as cephalosporins, clindamycin, and sulfamethoxazole.

Hidradenitis Suppurativa

Hidradenitis suppurativa sometimes referred to as acne inversa, is a chronic skin disease that affects the sweat glands and hair follicles. This condition causes bumps on the skin that can turn into painful boils. After they heal, scarring occurs.

The reason some people develop this condition is unknown. However, it’s thought that genetics and sex hormones may play roles.

Experts believe that hidradenitis suppurativa occurs when an abnormal growth of cells clogs hair follicles. This debris buildup eventually causes the follicle to rupture, leading to inflammation and scarring. Inflammation is an immune system response to aid in the healing process.

Symptoms

Symptoms of hidradenitis suppurativa include:

• Pain
• Swelling
• Pimple-like, pus-filled lesions
• Scarring

The condition typically affects areas where skin touches the skin, such as the underarms, groin, buttocks, and breasts.

Treatment

For mild cases, treatment usually involves taking anti-inflammatory medications. In addition, applying topical cleansing agents, such as acne washes and antibacterial soaps, can help.

Treatment for more severe cases include:

• Corticosteroids
• Antibiotics such as tetracycline and erythromycin
• Humira (adalimumab)
• Acne surgical procedures

Stye

A stye (hordeolum) is a painful, red bump that develops on the eyelid. A blockage of oil-producing glands in the eyelash follicle and Staphylococcus bacterial infection usually cause it.

A stye can form either on the outer or inner eyelid. A stye isn’t usually contagious, but a stye can release small amounts of bacteria. This bacteria can spread through physical touch or contact with items such as pillows.

Symptoms

Symptoms of a stye can include:

• Eyelid crusting
• Teary or itchy eyes
• Swelling on the eyelid
• Light sensitivity

Treatment

Styes typically clear without medical treatment in one to two weeks. Self-care methods may speed healing.

A common way to clear a stye is to clean the eyelid with a half-and-half solution of baby shampoo and water. In addition, you can place warm compresses on the eyelid for 10 to 15 minutes at a time, three to five times a day.

Seeing an ophthalmologist may be wise if your stye doesn’t improve with at-home care. They may prescribe topical or oral antibiotics and ensure there’s no underlying problem. Also, a doctor may surgically drain a stye if it blocks vision or does not clear with antibiotics.

Carbuncle

A single boil is called a furuncle. On the other hand, a carbuncle is a cluster of boils that form on a particular body area. Like a boil, a carbuncle results from a bacterial infection, usually by Staphylococcus aureus.

Symptoms

A carbuncle affects deeper layers under the skin, making symptoms more severe than a single boil.

Typically, the affected area is red and inflamed with multiple pus-filled boils. Carbuncles can develop anywhere on the body, but they commonly occur on the back and neck. A carbuncle may also include symptoms like:

• Pus-filled boils
• Fever
• Chills
• Scarring

Treatment

Although warm compresses may help it drain, it’s not uncommon for a carbuncle to need to be surgically drained by a doctor. A doctor may also prescribe antibiotics like trimethoprim-sulfamethoxazole and doxycycline, especially if it returns.

When to See a Doctor

Skin boils usually heal on their own, especially with proper self-boil treatment. However, some things may indicate an infection is brewing. If you notice any of the following, contact a healthcare provider:

• Fever
• Boils that last longer than one week
• Pain and discomfort
• Boils that return

A doctor can provide proper treatment and ensure there isn’t an underlying problem.