What Causes Rashes in Adults?

Rashes are not a disease themselves but a common symptom of another illness or condition. They have many causes, including allergic reactions, skin disorders, infections, and some chronic health conditions. Most rashes are mild and go away without treatment, but some can be a sign of a serious health issue. Read on to find out what rashes are, what causes them, and when you should see a doctor.

Dr Babak Ashrafi Clinical Lead for Service Development

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 21 Mar 2023

What is a Rash?

A rash is a change in the colour, texture, or feeling of your skin. They may or may not be accompanied by other symptoms. The appearance of a rash varies according to the cause.

Rashes may include:

  • a change in the colour of the skin (this is commonly redness but may also be purple, white, or brown)
  • itching
  • burning
  • pain
  • blisters
  • raised red patches (hives)
  • small bumps
  • irritation
  • swelling

Common Rashes in Adults

Rashes have many different causes ranging from mild to severe and even life-threatening. Let's take a look at some of the most common causes of rashes, what they look like, what causes them, and how they are treated.

Allergic reactions

Allergic reactions are a common cause of rashes. They are often caused by certain foods, medications, insect bites, or stings. This type of rash, known as hives, occurs when the body releases the chemical histamine into the blood. Histamine is normally released as part of an immune response to deal with a threat, but with allergies, your body overreacts and produces histamine when there is no threat present. Hives are normally raised, red patches on the skin that may itch or burn. They often go away by themselves within a few hours or days, but if they are causing you discomfort, you can take antihistamine tablets to help relieve symptoms. Antihistamine tablets are available over the counter but may cause side effects and are not suitable for everyone. Talk to your pharmacist and read the patient information leaflet carefully before taking antihistamines. If you suffer with hives you should contact a doctor as it’s important to find out if you have had a reaction to something. If you have hives and have difficulty breathing or lip or mouth swelling contact 999 as this is a sign of a serious allergic reaction.

Contact dermatitis

Contact dermatitis is a type of eczema that is triggered by contact with certain substances. It most commonly affects the hands and face and causes redness, dryness, itching, and cracked skin. Common triggers for contact dermatitis include soaps, detergents, latex, and frequent contact with water. It’s important to try and identify the trigger for your contact dermatitis so you can avoid it in the future. Treatments for contact dermatitis include:

  • emollient creams to hydrate and protect the skin
  • topical corticosteroids to reduce inflammation
  • steroid tablets may be prescribed to reduce inflammation in severe cases


Psoriasis is a chronic (long-term) skin condition where an overproduction of skin cells causes red, scaly, patches on the skin, most commonly on the elbows, knees, scalp, and lower body. It can also affect the nails and joints. The cause of psoriasis is not known, but it may be an auto-immune disease (where the body`s immune system attacks its own cells). There’s no cure for psoriasis, and it is normally a lifelong condition that flares up from time to time. Flare-ups can be triggered by various factors, including stress, smoking, alcohol, illness, or some medications. Treatment with creams like emollients and topical steroids can help to reduce symptoms.


Eczema (atopic dermatitis) is a chronic condition causing inflammation of the skin. Eczema causes dry skin and a red, itchy, scaly rash commonly around the elbows, knees, wrists, scalp, face, and neck, though it can occur anywhere on the body. Eczema is more common in people with asthma and allergies. It normally starts in childhood, and many children grow out of eczema by their mid-teens. There’s no cure for eczema, but treatment with emollient creams and topical steroids can help to relieve symptoms.

Seborrheic dermatitis

Seborrheic dermatitis is a condition that causes patches of red, scaly skin on the body. It commonly affects oily parts of the body such as the eyebrows, mouth, nose, and chest. Seborrheic dermatitis on the scalp is known as dandruff in adults and cradle cap in babies.

The condition is thought to be caused by an overproduction of a yeast called Malassezia yeast that normally lives on the body.

Seborrheic dermatitis is a long-term condition that flares up on occasion, particularly when you are stressed or unwell or in response to triggers like cold weather, some chemicals, or medications. Treatment aims to remove scales, reduce the itch, and soothe inflammation. It includes:

  • washing twice daily with a gentle cleanser that contains zinc
  • an emollient cream to help remove scales
  • prescription medications such as topical antifungal creams or shampoos
  • in severe cases, a topical corticosteroid or calcineurin inhibitor may be prescribed.

Razor bumps

Razor bumps (pseudofolliculitis barbae) occur after shaving or other hair removal techniques when the hair starts to grow back into the skin instead of outwards. They can occur wherever hair has been removed, such as the face, armpits, legs, and pubic area. Razor bumps typically show up as small red bumps that may be itchy or painful, or pustules (pus-filled blisters)

To help prevent razor bumps:

  • shave in the direction of hair growth
  • change your razor frequently or use an electric razor
  • avoid shaving too closely
  • look into alternative methods of hair removal such as laser hair removal or stopping shaving completely

Treatment for razor bumps includes:

  • Antiseptic lotions can help reduce the risk of infection.
  • Topical steroid creams can help to reduce inflammation
  • In severe cases, an antibacterial lotion or tablet may be prescribed

If your razor bumps are severe or keep coming back, make an appointment with your GP or dermatologist.

Reactions to plants

Reactions to plants vary according to the type of plant.

Stinging nettles cause an itchy, burning sensation and red, raised patches or red or white spots on the skin. This normally settles down within a few minutes. To treat nettle stings:

  • wash the affected area with soap and water as soon as possible
  • avoid scratching or rubbing the affected area
  • if symptoms continue for more than 2 hours, or if you develop symptoms of an allergy like facial swelling or shortness of breath, seek medical attention.

Serious reactions to plants are rare in the UK, but some plants can trigger allergic reactions in some people, and others contain irritant sap that can cause burning and blistering of the skin. If you experience a skin reaction or rash after coming into contact with plants, seek medical attention (take a sample of the plant with you to the hospital).

Heat rash (prickly heat)

Prickly heat or heat rash occurs when excessive sweating blocks pores resulting in small, itchy bumps on the skin, often with mild swelling. To treat prickly heat:

  • keep your skin cool as further sweating can irritate the skin. Wear loose, cotton clothing, take regular showers and drink plenty of water
  • apply a cool, damp cloth to the affected area a few times a day for up to 20 minutes
  • avoid harsh chemicals such as perfumed lotions or shower gels
  • avoid scratching or rubbing the affected area. After a shower, gently pat your skin dry.
  • speak to your pharmacist. Depending on your symptoms and general health, your pharmacist may recommend a topical treatment like calamine lotion, a mild hydrocortisone cream, or antihistamine tablets.

Drug rashes

Drug rashes or drug eruptions are rashes caused by reactions to certain medications. Some medications are more likely to cause a rash than others, including antibiotics (especially penicillins and sulphonamides) non-steroidal anti-inflammatory drugs (NSAIDs) and antiseizure medications.

Drug rashes range from being a minor or mild annoyance to serious and potentially life-threatening.

Types of drug rash include:

  • exanthematous rash. These rashes account for around 95% of drug rashes. They appear as reddened skin with small, raised, or flat lesions. They are usually itchy. Exanthematous rash normally goes away by itself in around 2 to 3 weeks.
  • hives are a common type of drug rash. They consist of raised patches of different shapes and sizes. On white skin, they are normally red or pink but may be harder to see on darker skin. They are often accompanied by itching and burning. Hives normally go away after a few days, but antihistamine tablets can help relieve symptoms.
  • erythroderma is a potentially life-threatening condition that causes a red, itchy rash over most of your body. The rash may grow scaly after a few days. Your skin may feel hot to the touch, and you may have a fever. If you think you may have erythroderma, seek immediate medical attention.
  • Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are very rare but potentially life-threatening conditions that cause large, painful blisters that burst, leaving open sores. These conditions require emergency treatment.
  • drug reaction with eosinophilia and systemic symptoms (DRESS syndrome) is another rare condition that can be life-threatening. It normally occurs 2 to 8 weeks after starting a new medication and starts as a red rash on the face and upper body. Other symptoms include fever, burning, itching, facial swelling, swollen lymph glands, and flu-like symptoms. DRESS syndrome can cause organ damage if not treated quickly. If you have symptoms of DRESS syndrome, seek immediate medical attention.


Shingles is a viral infection caused by the varicella-zoster virus, the same virus that causes chickenpox. It occurs in people who have had chickenpox previously as the virus stays dormant in the body and reactivates later, causing shingles. Symptoms of shingles include a painful, red rash that appears as blotches on one side of the face or body. The blotches turn into blisters that normally scab over in around 7 to 10 days and heal fully in between 2 and 4 weeks. Other symptoms of shingles include headache, fever, and upset stomach. Shingles is not contagious but can cause chickenpox in people who have not had it. If you have shingles you should avoid contact with:

  • pregnant women who have not had chickenpox
  • people with weakened immune systems
  • babies under 1-month-old (unless you gave birth to the baby)

Shingles may need treatment with an antiviral medication to speed up recovery and prevent complications. If you think you may have shingles use our photo diagnosis service or call your GP for advice.

Genital herpes

Genital herpes is a sexually transmitted infection (STI) caused by the herpes simplex virus (normally HSV-2). It is usually spread through vaginal, anal, or oral sex. Herpes symptoms commonly start with a tingling, itching, or burning sensation around the genital area. Within a few days, painful blisters may develop on the genitals, around the anus, and the inside of the thighs. These blisters burst, causing open sores that scab and crust over. Other symptoms may include pain when urinating (peeing), flu-like symptoms, and mild fever. Women may experience vaginal discharge. There’s no cure for herpes, and symptoms clear up on their own after a couple of weeks but may come back, particularly when you are unwell or run down. Antiviral drugs like aciclovir can relieve symptoms, speed up healing and reduce future outbreaks. Genital herpes is highly contagious, so do not have sex during an outbreak and use a condom to reduce the risk of passing the virus to your partner.

Oral herpes (cold sores)

Oral herpes (cold sores) is another form of herpes usually caused by the herpes simplex virus (HSV-1). The first symptom is usually tingling, burning, or itching around the lips and mouth, followed by the appearance of painful sores that blister and scab over. Symptoms normally clear up on their own in around 7 to 10 days, but treatment with a topical antiviral cream or antiviral tablets can relieve symptoms and speed up healing. There’s no cure for oral herpes, and outbreaks may continue throughout your life. Oral herpes is extremely contagious from when you first feel tingling until the cold sore is fully healed. Avoid skin-to-skin contact and sharing food and drinks with other people during this time.


Acne is a common skin condition, particularly among teenagers and young adults, though it can also affect older people. Acne occurs when hair follicles in the skin become blocked with oil, dirt, bacteria, and dead cells, causing a build-up of pus and bacteria under the skin. It is most common on the face, back and chest. The appearance of acne varies according to the type of acne that you have. Blackheads and whiteheads appear as small black, white, or yellow bumps on the skin, whereas cystic or nodular acne causes large painful lumps under the skin. Acne is not dangerous to your health but can cause long-term scarring and lead to psychological issues like depression and low self-esteem.

There are many over-the-counter remedies such as salicylic acid and benzoyl peroxide that work well for mild acne. For severe or stubborn acne, you may need a stronger prescription treatment.

Some medications that may be prescribed for acne include:

  • the combined contraceptive pill (in women)
  • topical antibiotics
  • oral antibiotics
  • azelaic acid
  • topical retinoids
  • oral retinoids

In addition to medications, some non-pharmaceutical treatments for acne include:

  • photodynamic light therapy
  • chemical peels
  • comedone extraction

Often acne clears up by itself once you leave your twenties. If your acne is severe (cystic or nodular acne), is causing you distress, or not going away, speak to your GP or dermatologist.


Impetigo is a skin infection that mostly affects young children, but anyone can get it. It is highly contagious but not usually serious. Impetigo normally starts with red sores or blisters that burst, leaving yellow or brown crusts on the skin. These crusts may be itchy or painful and can spread to other parts of the body. If you suspect you or your child has impetigo, make an appointment with your GP.

Impetigo is normally treated with antibiotic cream or sometimes antibiotic tablets if the infection is severe. Impetigo is highly infectious and can easily spread to other people or other parts of the body. You are no longer contagious (cannot spread impetigo) if:

  • it has been 48 hours since starting the medication prescribed by your GP
  • The patches have dried out and crusted over

To reduce the risk of spreading impetigo:

  • keep sores, blisters, or crusts clean and dry and cover with loose clothing or a gauze bandage
  • avoid touching sores, blisters, or crusts
  • avoid contact with children or people with a weakened immune system
  • don’t share blankets, flannels, or towels
  • don’t prepare food for others
  • stay away from communal areas like the gym
  • don’t play contact sports like football or rugby
  • stay home from work or school until you are no longer contagious
  • wash your hands frequently, especially after coming into contact with the sores or crusts
  • wash bed linen and towels at a high temperature
  • tell your GP if you suspect impetigo. They may prefer to schedule a telephone appointment or video call


Ringworm is a common fungal infection. Unlike the name suggests, it is not caused by worms. Ringworm causes a ring-like, circular rash that may be red, silver, or darker than your normal skin. It may also be dry, scaly, itchy, or swollen. Ringworm can occur anywhere on the body. If it occurs on the scalp, it is known as tinea capitis and on the groin as jock itch. It may spread and cover larger areas of the body. Ringworm is passed on through:

  • close contact with an infected person or animal
  • touching infected objects or surfaces
  • rarely, infected soil

Treatment for ringworm is with an antifungal cream, gel, or spray. Your pharmacist can recommend one for you. You need to use the treatment every day for as long as your pharmacist tells you to, even if the rash has cleared up.

Make an appointment with your GP if:

  • your ringworm has not responded to treatment from a pharmacy
  • you have a weakened immune system
  • you have ringworm on your scalp

When Should I See a Doctor About My Rash?

Rarely rashes can be a sign of serious diseases such as septicaemia, severe allergic reaction (anaphylaxis), or Stevens-Johnson syndrome.

Go to the hospital immediately if:

  • your rash doesn’t fade when you press a glass against your skin
  • you have swelling of the face, lips, and tongue, shortness of breath, or difficulty breathing
  • your rash is sudden and spreads rapidly
  • you have multiple blisters or open sores
  • your rash is painful
  • your rash is infected. Signs of infection include green, or yellow fluid, foul odour, swelling, pain, and heat
  • you have a rash and also have a fever, vomiting, neck stiffness, a headache, drowsiness, seizures, fast heart or breathing rate, dizziness or changes to your vision

Contact your GP if:

  • your rash lasts for longer than 2 days
  • your rash is spreading or getting worse
  • you are getting rashes frequently
  • you feel generally unwell
  • you have angioedema (swelling under the skin)

How Do I Know What’s Causing My Rash?

Sometimes it can be difficult to identify the cause of your rash. If you are worried about a rash, make an appointment to see your GP or dermatologist.

At Superdrug, we’ve created an Online Skin Diagnosis service to help you identify the cause of your rash. Simply upload at least 2 clear photos of your rash, and one of our doctors will examine it and contact you to discuss your diagnosis, advice, and recommended treatment within 24 hours.


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