Read on to learn more about what can cause a rash on the back and how to treat it. This guide also discusses when to contact a doctor and how they diagnose the cause of a back rash.
You may experience a rash on the back for several different reasons. These include:
- contact dermatitis as a result of a reaction to an allergen or irritant
- atopic dermatitis or eczema
- infection or underlying health condition
Contact dermatitis
Contact dermatitis is a relatively common condition that occurs when your skin comes into direct contact with an allergen or irritant. You may experience skin irritation or an allergic reaction after exposure to the substance or material.
Common causes of allergic contact dermatitis include:
- poison ivy or poison oak
- nickel, cobalt, and other metals
- fragrances or perfumes
- latex and other rubber products
- textiles
- plants
Common causes of irritant contact dermatitis include:
- detergents and soaps
- antibacterial products
- perfumed toiletries
- solvents
- machinery oil
- disinfectants
- cement
- dust, soil, and powders
- hard, chalky, or chlorinated water
- plants
Learn more about contact dermatitis.
Atopic dermatitis or eczema
Atopic dermatitis, also called eczema, is an inflammatory skin condition that typically begins before age 5. However, adolescents and adults can also develop eczema.
Exposure to allergens can worsen eczema. Common triggers for eczema include:
- cosmetics
- detergents
- soaps
- fragranced lotions
- perfumes
- cleaning products
Other causes of a rash on the back
Other causes of a back rash include underlying health conditions and viral or bacterial infections. Systemic rashes can cause a rash on the chest, back, or other areas of your body.
Possible infections and conditions that can cause a rash include:
- cellulitis
- chickenpox
- measles
- shingles
- fifth disease or erythema infectiosum
- Lyme disease
- ringworm
- lupus
- mononucleosis (mono)
- staph infection
- pityriasis versicolor
- pityriasis rosea
An infant may develop a rash on their back for many reasons. However, it is often not a cause for concern.
Possible causes for a baby’s back rash include:
- scarlet fever, with a rash that feels like sandpaper and looks like pinpricks
- measles, with a rash that usually begins on the head or neck
- prickly heat rash, which occurs due to heat and sweat
- hives, which appear as an itchy raised rash after an allergic reaction
- ringworm, which is a dry, ring-shaped rash
- chickenpox, which are small spots that itch and can blister
- scabies, which occurs when tiny mites burrow under the skin
- meningitis, with a rash that may fade if you apply pressure to it, such as with a drinking glass
Find out when to take a baby to a doctor for a back rash.
The symptoms you experience with a back rash can depend on the condition’s cause.
Symptoms of contact dermatitis
Symptoms of contact dermatitis include:
- inflamed or irritated skin
- dry or cracked skin
- thickened skin
- blisters
- red or discolored skin
- burning or stinging sensation from irritants
- itchiness as a result of contact with allergens
If you experience a reaction to an irritant, symptoms will typically appear within 48 hours. Symptoms of a reaction to allergens may take a few days to develop.
Symptoms of atopic dermatitis
Symptoms of atopic dermatitis, or eczema, include:
- red or discolored patches of skin, particularly in elbow and knee folds
- itchiness
- skin that is dry, cracked, and sometimes bleeding
- possible blisters
Children tend to experience eczema in the following places:
- cheeks
- inner elbows
- behind the knees
Children and adults tend to get eczema:
- on the hands and feet
- on the arms
- behind the knees
Treatments for a rash on the back can depend on the underlying cause.
Treatments for contact dermatitis
One way to treat contact dermatitis is to avoid the allergen or irritant that has caused the rash.
Other treatments for contact dermatitis include:
- moisturizers or lotions to prevent skin from becoming dry
- topical corticosteroids to reduce inflammation
- oral corticosteroids if the rash covers a large area of your body
- antihistamines to alleviate itchiness
Treatments for atopic dermatitis
Treatments for atopic dermatitis include:
- topical corticosteroids for inflammation
- antihistamines to reduce itchiness
- ointments and petroleum jelly for milder cases
- avoiding known triggers
Other treatments
Other possible treatments for a rash on the back include:
- UVB light therapy for conditions such as pityriasis rosea
- antifungal medication and creams for conditions such as pityriasis versicolor
- bathing in a cool oatmeal bath
A rash can indicate a mild allergic reaction. However, in some cases, it can also be a symptom of a severe allergic reaction or anaphylaxis.
Symptoms of anaphylaxis can include:
- an itchy rash or hives
- swollen throat, lips, or tongue
- breathing difficulties
- feeling dizzy
- fainting
- stomach pains
- vomiting
- diarrhea
- uterine cramps
You may experience only some symptoms of anaphylaxis.
Seek immediate medical attention if you experience a severe allergic reaction or anaphylaxis. If you carry an EpiPen or similar epinephrine auto-injector device for a known allergy, administer this before seeking medical help.
View the slideshow below for pictures of different types of back rash.
Contact a doctor if you have a rash on your back and any of the following apply:
- The rash covers a large area or is in other areas of your body.
- You have a fever.
- The rash appears suddenly and spreads quickly.
- The rash blisters.
- You experience pain with the rash.
- The rash becomes infected.
If you have a rash on your back, your doctor will perform a physical examination. They will also carry out tests to help to determine the cause of the rash.
The type of tests can depend on any other symptoms you present but can include:
- allergy skin tests, such as a patch test
- blood tests, either alongside or instead of allergy skin tests
- skin biopsy, which can detect conditions such as eczema
During a patch test, your doctor will place patches of common allergens and irritants against your skin. After around 2 days, your doctor will remove the patches to observe any reactions.
Learn more about allergy skin tests.
Your doctor will also ask you questions about your rash and other symptoms. These questions might include:
- When did the rash begin?
- Are you taking any medication?
- Do you have any allergies?
- Did the rash start in one location and spread to another?
- Does the rash cause any itching or scaling?
- Do you have any other symptoms?
- Have you tried any new products recently, such as soaps, perfumes, or sprays?
- Have you spent a lot of time outdoors lately?
You may experience complications of an underlying condition or infection that causes the rash. It is important to contact your doctor if your rash does not respond to over-the-counter medication or if it begins to spread. Early diagnosis of the cause can help reduce your risk of complications.
You may also get an infection if you scratch an itchy rash. Signs of an infected rash include:
- swelling
- crusting
- pain
- warmth in the area
- streaking
- green or yellow fluid
Contact your doctor if your rash becomes infected.
You can take steps to prevent developing a rash on the back, particularly when it occurs due to contact dermatitis.
Steps you can take to reduce your risk of a rash on the back include:
- avoiding known irritants and allergens
- avoiding using fragranced or perfumed cosmetics or toiletries
- wearing a shirt when outdoors or around known irritants or allergens
- wearing gloves to prevent scratching any itches, such as with atopic dermatitis
A rash on the back can occur for many reasons. It can happen as a result of contact with an allergen or irritant. It can also occur due to an infection or underlying health condition.
Treatments for a back rash typically include corticosteroids to reduce inflammation and lotions to soothe pain and dryness. Antihistamines can also help alleviate itchiness.
Contact your doctor if you have concerns about a rash on the back. You should also seek medical advice if the rash appears suddenly, spreads, or becomes infected.
