Skin infections fall into five types based on what causes them: bacterial, viral, fungal, parasitic, and mycobacterial. Each type looks and feels different on the skin, spreads in different ways, and responds to different treatments. Understanding which category an infection belongs to is the first step toward knowing what you’re dealing with and how it gets resolved.
Bacterial Skin Infections
Bacterial infections are the most common type of skin infection. They’re typically caused by Staphylococcus aureus or Streptococcus bacteria, which can enter through cuts, scrapes, insect bites, or any break in the skin’s surface. The three you’re most likely to encounter are impetigo, cellulitis, and folliculitis.
Impetigo is highly contagious and most often affects children. Its hallmark is honey-colored crusts that form over sores, usually around the nose and mouth. Cellulitis runs deeper, infecting the layers beneath the skin’s surface. It shows up as an area of expanding redness that feels warm, swollen, and painful to the touch. Folliculitis looks like small pimple-like bumps clustered around hair follicles, often appearing where skin is regularly shaved or irritated by tight clothing.
A particular concern with bacterial skin infections is antibiotic resistance. Community-acquired MRSA (methicillin-resistant Staphylococcus aureus) has become increasingly common, especially among people living in close quarters, athletes in contact sports, and military personnel. Resistance patterns are shifting enough that treatment guidelines are regularly updated. Growing Streptococcal resistance to certain antibiotics, for example, prompted revised clinical guidance as recently as January 2026.
Viral Skin Infections
Viruses cause several familiar skin conditions: shingles, warts, herpes simplex, and molluscum contagiosum. These infections tend to look quite different from bacterial ones. Instead of spreading redness or pus, viral infections typically produce clusters of small fluid-filled blisters or distinct growths on the skin.
Herpes simplex (which causes cold sores and genital herpes) and shingles both produce grouped blisters sitting on a red, inflamed base. Shingles follows a nerve path, so the blisters usually appear in a band or strip on one side of the body. Warts, caused by human papillomavirus, appear as rough, raised growths. Molluscum contagiosum produces small, dome-shaped bumps with a dimple in the center and is especially common in children.
Most viral skin infections can’t be “cured” the way bacterial ones can. The virus often stays in the body after symptoms clear, and outbreaks may recur. Treatment focuses on managing symptoms, shortening outbreaks, and reducing the chance of spreading the virus to others.
Fungal Skin Infections
Fungal infections are caused by two main groups of organisms: dermatophytes and yeast. Dermatophytes are fungi that feed on keratin, the protein in your skin’s outer layer, hair, and nails. They don’t infect living tissue, which is why these infections stay on the surface.
Dermatophytes cause the family of infections commonly called ringworm, though no worm is involved. The name changes depending on where it appears: athlete’s foot on the feet, jock itch in the groin and inner thighs, and ringworm on the scalp or body. These infections typically cause scaling, discoloration, and ring-shaped patches with clearing in the center.
Yeast infections are a separate category. Candida albicans is a yeast that naturally lives on your body without causing problems, but under certain conditions it can overgrow and trigger infection. Candida causes oral thrush, some types of diaper rash, vaginal yeast infections, and skin fold infections (called candidal intertrigo) in areas where skin rubs together, like under the breasts or in the armpits. Warm, moist environments encourage both types of fungal infection, which is why they’re common in skin folds and sweaty areas.
Parasitic Skin Infections
Parasitic skin infections are caused by tiny organisms that burrow into or live on the skin. The two most well-known examples are scabies and lice.
Scabies is caused by a microscopic mite that tunnels just beneath the skin’s surface. The most recognizable symptoms are intense itching, especially at night, and a pimple-like rash. You may notice tiny burrow lines on the skin, particularly between the fingers, on the wrists, elbows, waistline, or buttocks. In infants and very young children, the rash often appears on the head, face, neck, palms, and soles of the feet.
Scabies spreads primarily through direct, prolonged skin-to-skin contact. Less commonly, it spreads through shared clothing, towels, or bedding. A person can transmit scabies even before they develop symptoms, which makes it especially tricky in crowded settings where close contact is frequent. Lice operate similarly, attaching to hair or clothing and feeding on blood, causing itching at the site of bites.
Mycobacterial Skin Infections
The fifth and least common type involves mycobacteria, a family of slow-growing bacteria that behave differently from the typical staph and strep that cause most bacterial skin infections. The best-known mycobacterial skin infection is cutaneous tuberculosis, but nontuberculous mycobacteria can also infect the skin after surgery, tattoo procedures, or exposure to contaminated water.
Mycobacterial infections are often slow to develop. They may start as a painless lump or nodule that gradually enlarges over weeks or months. Because they don’t look like a typical infection and progress so slowly, they’re frequently misdiagnosed initially. Treatment usually requires a prolonged course of targeted antibiotics, sometimes lasting several months.
Who Is Most at Risk
Certain conditions make skin infections of any type more likely. Diabetes is a major risk factor, increasing the chance of infection-related complications roughly fivefold. The reasons are interconnected: diabetes reduces blood flow to the skin, slows healing, and weakens immune defenses. Obesity, heart disease, kidney disease, and any condition that suppresses the immune system also raise the risk significantly.
Lifestyle factors matter too. Intravenous drug use creates direct entry points for bacteria. Hot tub use is associated with a specific type of bacterial folliculitis. Breaks in the skin from cuts, bites, surgical wounds, or even dry, cracked skin all give infections an opening. Older adults face higher risk because aging naturally weakens the immune response and thins the skin barrier.
Warning Signs of a Spreading Infection
Most skin infections stay localized and resolve with appropriate treatment. But when an infection enters the bloodstream, it can trigger sepsis, a life-threatening response. Early signs include fever, sweating, shivering, rapid breathing, and a fast heart rate. Confusion and lightheadedness suggest the infection is progressing.
For skin infections specifically, watch for redness that is rapidly expanding, skin that feels increasingly warm and painful, or pus collecting beneath the surface. Septic shock, the most dangerous stage, causes difficulty breathing, cool or blue-tinged skin, drastically reduced urination, and extreme confusion or difficulty staying conscious. These symptoms require immediate emergency care.