The 10 Most Common Skin Diseases

The most common skin conditions usually appear with symptoms such as redness, swelling, itching, and epidermal peeling. Some have a cure and others don't.

Written and verified by el biólogo Samuel Antonio Sánchez Amador.

Last update: 19 September, 2023

The skin is the largest organ in the human body, as an average adult has 21.5 square feet and 11 pounds of this tissue covering their body. This layer and its attachments (hair, nails, and sebaceous and sweat glands) make up the integumentary system, which is responsible for the protection of the body. Even so, there are certain common skin diseases that prevent it from working properly.

According to professional studies, skin diseases correspond to 1.79% of the global pathological burden in the world. It’s not surprising, as today, more than 3000 skin diseases have been detected, which range from small pimples to very serious infected lesions. If you want to know more about this set of clinical pictures, keep reading.

What are the most common skin diseases?

As stated above, the skin is the largest organ in the human body. Its importance is vital for survival because together with mucous membranes, saliva, and tears, it represents the primary biological barrier that prevents the passage of microorganisms. An open wound is a gateway for bacteria, so keeping your skin healthy is essential to avoid complications.

Before exploring the most common skin disease, we find it interesting to frame them in a general epidemiological situation. The American Academy of Dermatology (AAD) provides us with the following information of interest:

• In the United States alone, 84.5 million people have a skin disease. This translates to 1 in 4 adults.
• An estimated $ 75 billion a year is spent in this region to diagnose and treat people with skin conditions.
• Studies estimate that epidermal diseases are the fourth most common cause of discomfort in humans. Chronic conditions (such as psoriasis or atopic dermatitis) have a very high burden of disease.

Interestingly, up to 2/3 of people with dermatological conditions don’t know they have them. For this reason, it’s essential to be able to detect any strange clinical signs on the skin before they become serious and an urgent consultation is necessary. Discover with us the 10 most common skin diseases.

1. Acne vulgaris

Typical acne, also known as acne vulgaris, is the most common dermatological condition in high-income countries. This pilosebaceous unit disease affects more than 40 million people worldwide, including girls as young as 11 and 12 years old and boys as young as 12. Up to 40% of the adult population has skin blemishes and a propensity for acne.

Acne begins when a hair follicle becomes clogged, either by excess oil or by too rapid keratinization of the skin. Therefore, a “microcomedone” is formed, which can be open (a blackhead) or closed (a pimple). This causes fat to accumulate in the follicle, the perfect place for the Cutibacterium acnes bacteria to develop.

As this bacterium proliferates and feeds on the fatty acids of the hair follicle, it degrades some components of the dermis and epidermis and promotes an inflammatory reaction. It’s this reaction that promotes the appearance of papules and pustules, which are much more obvious and painful than a simple pimple.

With this disease process in mind, it should be noted that there are many types of acne. According to their severity, the following scale is suggested when the injuries are mainly on the face:

• Mild grade 1 acne: Comedones are the main lesions and inflammation is rare. Papules and pustules are very few, if any, with figures of less than 10 on the entire face.
• Grade 2: Between 6 and 20 inflammatory lesions on the middle of the face. The trunk can also be affected, and papules and pustules are much more common.
• Grade 3: Between 21 and 50 inflammatory lesions in the middle of the face. There are up to 100 papules and pustules on the face, with infiltrating, painful, and reddened lesions. This type of acne leaves scars.
• Very severe or grade 4 acne: Nodular lesions are multiple and can affect various parts of the body. It requires immediate medical attention.

Many mild acne conditions are self-limited and can be addressed with general skin care, but not all are. Benzoyl peroxide, topical antibiotics, and azelaic acid have relevant anti-inflammatory activity in moderate or severe conditions, for example.

2. Atopic dermatitis

Atopic dermatitis is one of the most common skin diseases and causes epidermal redness and general itching. It’s a chronic condition that usually presents with sporadic spikes and is much more common in children. As indicated by epidemiological studies, the prevalence is 10 to 20% in the child population and 1 to 3% among adults.

There are many theories that attempt to explain the causes of atopic dermatitis, but up to 70% of patients have or have had relatives with the same condition, so it’s believed that much of its attribution is genetic. Some of its most common symptoms are the following:

• Very dry skin
• Itching that can be severe, especially at night
• Itchy red patches on the hands, feet, ankles, neck, and other parts of the body
• Small pustules that can drain fluid if scratched too much
• Scaly, thickened, and cracked skin

Creams to control itching and repair the skin are the most commonly used for this condition. In any case, sometimes antibiotic creams are necessary, as bacterial infections are established in the affected area.

3. Shingles

Shingles is a rash or blisters on the skin caused by the varicella-zoster virus (VZV). Before vaccination existed, 99.6% of the population over 40 years old showed signs of having had VZV.

Interestingly, this virus remains chronically inactive in the patient’s trigeminal nerve and spinal ganglion area. Therefore, after having chickenpox during childhood, there’s a 10-20% chance that the pathogen will reactivate and cause cutaneous herpes zoster.

Most of the time, symptoms only affect a specific part of the body, as indicated by the Mayo Clinic. Some of the most relevant are the following:

• Tingling, numbness, pain, and burning in the affected area.
• Excessive sensitivity to rubbing and touch.
• Localized skin rash. This clinical sign appears between 1 and 14 days after the onset of pain.
• Fluid-filled blisters that end up bursting and crusting.
• Itching, fever, fatigue, and sensitivity to light. The last 3 symptoms are slightly less common.

In addition to allowing the immune system to kill the infection, fortunately, there’s an antiviral drug, acyclovir, that produces excellent results in treating the disease.

4. Urticaria

The term “urticaria” refers to the appearance of itchy reddish epidermal welts. It’s one of the most common skin diseases, as it’s estimated that between 15 and 25% of the population has suffered from this clinical picture at least once in their life. It’s more common in women, and its epidemiological peak is between the ages of 20 and 40.

There are many causes of hives, whether or not they’re immune. These include drug allergy, food intolerance, insect bites, contact with cosmetics, and interaction with some toxic elements. It’s a very common condition that usually disappears on its own, although if it lasts it requires intervention.

5. Sunburn

Although it’s not a common disease, sunburn deserves an honorary position on this list. As indicated by the Medscape portal, in the United States, up to half of the adult population reports at least one burn during the summer season.

Due to excessive exposure to UV rays, the skin becomes red, very sensitive to the touch, and is more prone to developing various types of cancers (melanoma, squamous cell, and basal cell). In the most severe burns, blisters usually appear in the initial stage and epidermal peeling once the area begins to heal.

In most places, solar incidence is highest between 10 a.m. and 4 p.m. It’s important to apply abundant maximum-protection sunscreen to anyone who’s going to spend a considerable time exposed to the sun, either for fun or necessity.

6. Contact dermatitis

Contact dermatitis is a type of skin rash typical of the dermatitis picture already described, but it occurs due to direct contact with a substance or due to an allergy to it. Soaps, cosmetics, certain fragrances, metals (and derivatives, such as rings and earrings), plants, and many other compounds can cause this skin condition.

Interestingly, this disease affects twice as many women as men and it usually begins between 12 and 16 years of age. A variant of it is occupational contact dermatitis (OCD), which is one of the first occupational diseases in various sectors. This type of dermatitis is also more common in those individuals who are already atopic.

There are 2 types of clinical pictures within this category:

1. Irritant contact dermatitis: It’s not caused by an allergy but by contact with a substance that acts as an irritant, either due to its pH, chemical composition, or other factors. The reaction can be direct or develop after successive exposure to the problem compound.
2. Allergic contact dermatitis: In this case, the reaction is triggered by an allergen that doesn’t have to have irritating properties, such as drugs, fragrances, fabrics, latex, preservatives, and many more.

Treatment always consists of detecting the problem allergen and minimizing your exposure to it. Topical corticosteroids can be prescribed when reactions appear, but it’s very important not to abuse them.

7. Psoriasis

Psoriasis is another of the most common skin diseases. In it, red spots appear on the skin that cause itching, especially in the areas of the knees, elbows, trunk, and scalp. It’s a long-term chronic disease that has no cure, but it can be managed with corticosteroids, retinoids, vitamin D analogs, and other compounds.

This disease is multifactorial and very complex, so an exact trigger can’t be cited in all cases. In any case, it’s known that it has a clear genetic component, as homozygous twins with a family history have a 60% probability of presenting it jointly throughout their lives.

8. Athlete’s foot (tinea pedis)

Athlete’s foot is a clinical condition that falls into the category of dermatophytoses because it’s caused by infection by dermatophyte fungi. These microorganisms feed on the keratin of the epidermis and are frequently located on the nails, groin, interdigital spaces, scalp, and any area with fine skin on the body.

Fungi cause peeling, itching, stinging, and burning of the foot. In addition, it’s a very contagious condition, so it’s important to avoid sharing footwear or hygiene material with anyone who suffers from this condition. It should be noted that dermatophytoses affect 15% of the world population, 20% if we only take into account adults.

9. Basal cell cancer and squamous cell cancer

Unfortunately, among the most common skin diseases, we have to mention cancer. Basal cell and squamous cell cancers are the most common types of skin neoplasms. They start in the superficial part of the skin (epidermis) and are often related to sun exposure.

About 8 out of 10 skin cancers are basal cell cancers, according to the American Cancer Society. They tend to grow very slowly and rarely metastasize, but if left untreated, they can spread significantly to bone, muscle, and other adjacent tissues.

At the same time, almost 2 out of 10 skin cancers are squamous cell cancers. They’re also quite localized, although they have a greater tendency to spread than the previous ones. Surgery usually fixes many of the conditions, although radiation therapy, freezing, curettage, and electrodesiccation are also sometimes necessary.

10. Rosacea

Rosacea is another of the most common skin diseases. In it, redness, visible blood vessels, and, in some cases, red bumps filled with pus appear on the skin. It can be confused with acne, but it’s an independent clinical picture that requires another type of approach.

The causes of rosacea are unknown, but there are certain triggers that can cause flare-ups. Among them, we highlight the following:

• Hot drinks, those prepared with alcohol, and spicy foods
• Extreme temperatures and environmental actions, such as the sun or the wind
• Strong emotions
• Exercise
• Vasodilator drugs
• Certain cosmetics

In most cases of rosacea, topical medications are used to reduce redness, oral antibiotics, and some drugs to reduce acne. Laser therapies and phototherapy are conceived in the most severe conditions that don’t respond well to pharmacological action.

Common skin diseases: A common conglomerate

Common skin diseases are very interesting, and many of them have similar clinical elements. Rash, red patches, itching, and peeling are the symptoms of most skin conditions. Any picture of this type or similar deserves a visit to a doctor because you never know if you’re dealing with an infection or an autoimmune condition.

Also, many of these conditions are chronic and can’t be cured. If you suffer from psoriasis, atopic dermatitis, rosacea, or similar skin diseases, don’t hesitate to seek specialized professional support. Although you can’t get rid of the disease completely, it’s possible that the symptoms are much milder.