What Is a Rash?
A rash is any change in the skin that affects its color, texture, appearance, or feel. Rashes on the skin may appear as redness, bumps, scaling, dryness, blisters, peeling, dark spots, light spots, swelling, cracking, or irritation.
Some rashes are mild and temporary. Others may signal an infection, an allergic reaction, an autoimmune condition, or an internal medical problem that needs prompt attention.
Not every rash is dangerous—but every persistent, painful, itchy, spreading, or unexplained rash deserves proper evaluation.
At Aglow Dermatology, we evaluate rashes in all skin types, including skin of color, where redness may appear differently and inflammation may lead to post-inflammatory hyperpigmentation or scarring.
Common Symptoms of Rashes
Rashes can look and feel very different depending on the cause.
Common symptoms include:
- Itching
- Burning
- Stinging
- Pain or tenderness
- Dryness
- Peeling or scaling
- Redness or discoloration
- Swelling
- Crusting
- Oozing
- Blisters
- Raised bumps
- Cracks in the skin
- Dark marks left behind after healing
Some rashes are uncomfortable. Some are completely asymptomatic and only noticed visually.
What Causes Rashes?
Rashes may be caused by something happening on the skin or by something happening inside the body.
External Causes of Rashes
These include:
- Allergic reactions
- Irritation from skin products
- Fragrances and preservatives
- Soaps and detergents
- Cosmetics and hair products
- Jewelry or metals like nickel
- Poison ivy and poison oak
- Heat and sweating
- Friction
- Sun exposure
- Insect bites
- Fungal infections
- Bacterial infections
- Viral infections
Internal Causes of Rashes
These include:
- Autoimmune diseases like lupus
- Psoriasis
- Eczema
- Drug reactions
- Hormonal changes
- Pregnancy-related rashes
- Stress-triggered inflammation
- Internal infections
- Nutritional deficiencies
- Liver disease
- Kidney disease
- Thyroid disease
Sometimes a rash is the first sign of an internal medical condition.
Types of Common Rashes
Eczema (Dermatitis)
Eczema is one of the most common causes of rashes on the skin.
It often causes:
- Dryness
- Itching
- Redness
- Scaling
- Cracking
- Thickened skin
Types of Eczema
Atopic Dermatitis
Often associated with asthma, allergies, and sensitive skin. Common in children but also affects adults.
Internal link: Eczema Treatment
Allergic Contact Dermatitis
Occurs when the immune system reacts to something touching the skin.
Examples include:
- Poison ivy
- Fragrance allergy
- Hair dye reactions
- Nickel allergy
- Preservatives in skincare
Internal link: Allergy Testing
Irritant Contact Dermatitis
Caused by repeated exposure to irritating substances rather than a true allergy.
- Frequent handwashing
- Cleaning products
- Hand sanitizer
- Saliva around the mouth
- Harsh acne products
Nummular Dermatitis
Coin-shaped itchy patches often found on the arms and legs.
Seborrheic Dermatitis
Often affects:
- Scalp
- Eyebrows
- Around the nose
- Ears
- Chest
It may be confused with dandruff.
Internal link: Seborrheic Dermatitis vs Dandruff
Psoriasis
Psoriasis is an inflammatory immune-mediated skin condition that causes thick, scaly plaques.
Common areas include:
- Scalp
- Elbows
- Knees
- Lower back
- Nails
It may itch, crack, bleed, or become painful.
Lupus Rashes
Psoriasis is an inflammatory immune-mediated skin condition that causes thick, scaly plaques.
- Butterfly rash across the cheeks and nose
- Scalp inflammation with hair loss
- Discoid lupus lesions
- Sun-sensitive rashes on exposed skin
Because lupus may affect internal organs, diagnosis often involves both skin evaluation and medical testing.
Fungal Rashes
Some rashes look like ringworm—and sometimes they are.
Common fungal rashes include:
- Ringworm (tinea corporis)
- Athlete’s foot
- Jock itch
- Yeast infections
- Intertrigo under the breasts or skin folds
Fungal rashes often worsen with heat, sweat, and moisture.
Intertrigo and Rashes in Skin Folds
Rashes under the breasts, in the groin, under the abdomen, and between skin folds are very common.
These may involve:
- Friction
- Moisture
- Yeast overgrowth
- Bacterial infection
- Irritation
This is similar to diaper rash and often requires treating both inflammation and infection.
Drug Rashes
Medications can trigger skin eruptions.
Examples include:
- ScAntibiotics
- Blood pressure medications
- Pain medicationsalp
- Seizure medications
- Supplements
- New skincare products mistaken for medication reactions
Drug rashes can be mild—or serious and urgent.
Never ignore a widespread rash after starting a new medication.
Rashes from Stress
Stress can worsen:
- Eczema
- Psoriasis
- Hivesees
- Seborrheic dermatitis
- Acne
- Itching without visible rash
Stress may not be the sole cause, but it often makes inflammatory skin conditions worse.
Sun Rashes
Some people develop rashes after sun exposure.
This may be due to:
- Lupus
- Polymorphous light eruption
- Medication-related sun sensitivity
- Heat rash
- Photodermatitis from products applied to the skin
Rashes During Pregnancy
Pregnancy can trigger:
- Itching
- Stretch-related irritation
- Melasma
- PUPPP rash
- Hormonal flares of eczema or psoriasis
Some pregnancy rashes require prompt evaluation.
Rashes Around the Mouth and Lips
These may include:
- Perioral dermatitis
- Irritant dermatitis
- Lip eczema
- Cheilitis
- Angular cheilitis
Cracking at the corners of the mouth is common and may be caused by irritation, yeast, saliva, or nutritional deficiency.
Rashes Around the Eyes
The eyelid skin is thin and sensitive.
Common causes include:
- Allergic reactions
- Eczema
- Contact dermatitis
- Cosmetic irritation
- Seborrheic dermatitis
Eye-area rashes require careful treatment because many strong topical medications are not appropriate near the eyes.
Lichen Planus and Other Less Common Rashes
Other inflammatory rashes include:
- Lichen planus
- Pityriasis rosea
- Hives
- Vasculitis
- Rosacea
- Sarcoidosis
- Dermatomyositis
Some rare rashes provide important clues to overall health.
How Dermatologists Diagnose Rashes
Sometimes a rash can be diagnosed immediately with a history and physical exam.
Sometimes additional testing is needed.
This may include:
- Skin examination
- Review of medications
- Allergy history
- Blood tests
- Skin biopsy
- Fungal testing
- Bacterial culture
- Patch testing
- Autoimmune workup
The goal is not just to treat the rash—but to understand why it is happening.
When Should You See a Dermatologist for a Rash?
You should see a dermatologist if your rash:
- Lasts more than 1–2 weeks
- Keeps coming back
- Is painful
- Is spreading
- Causes swelling
- Is blistering
- Involves the face or eyes
- Affects the scalp with hair loss
- Happens after starting a medication
- Occurs with fever or feeling sick
- Leaves dark marks or scars
- Does not improve with over-the-counter treatment
Rash Treatment Options
Treatment depends on the cause.
This may include:
- Prescription creams
- Anti-inflammatory medications
- Antifungal treatment
- Antibiotics
- Allergy testing
- Oral medications
- Light therapy
- Biologic medications
- Lifestyle and trigger management
Accurate diagnosis matters because treating the wrong rash can make it worse.
Schedule an Evaluation for Your Rash
If you have an itchy, painful, persistent, or unexplained rash, don’t guess.
Whether it is eczema, psoriasis, lupus, a fungal rash, allergic contact dermatitis, seborrheic dermatitis, or something less common, proper diagnosis is the first step.
At Aglow Dermatology, we help patients identify the cause of rashes and create personalized treatment plans for healthier skin.
Book Your Appointment
If you have rashes on the skin that are not improving—or you are not sure what your rash is—schedule a consultation today.