A rash can be a symptom of another condition (secondary), or occur as a result of skin irritation (primary). Most skin rashes are harmless and clear up quickly. They may be indicative of a problem requiring medical attention however in some cases.
- Common types of rashes include contact dermatitis and hives
- Often associated with itchiness and swelling
- Can be treated with creams, ointments or antibiotics
If you want to speak to someone online about a rash, our GMC-registered clinicians are available to consult with via our video consultation service, between 9.30am and 4.30pm, five days a week.
There are many possible causes of a rash. It may be triggered by skin irritation, an allergic reaction, or by an underlying medical condition.
The most common cause of a rash is contact dermatitis, which’s a type of eczema. This occurs when the skin comes into contact with something that leads to an itchy and inflamed rash. It may be a certain type of detergent for washing, material in clothing, or a chemical used in making plastic.
Medication is another very common cause of a rash, as the body can have an allergic reaction to a particular ingredient in the treatment.
A virus is also a common cause of a rash. These rashes are nonspecific, because their presence alone is not enough to establish that the virus is the cause, as other symptoms have to be present such as a high temperature. Viral rashes include measles and chickenpox. Meningitis is another type of infection which can result in a rash, and may be viral or bacterial.
Types of rashes and their symptoms
Rashes can come in many forms, and the vast majority aren’t serious. Sometimes they cause just a reddening of the skin with raised bumps. In other instances they may also be accompanied by other symptoms, such as blisters and pustules.
Erythema, or redness of the skin, is a common rash which can stem from many conditions; for example, a skin infection such as cellulitis, sunburn, or an allergic reaction. Inflammation of the blood vessels, called vasculitis, is associated with several different conditions and can cause erythema.
There are several different types of erythema, with many different causes. For instance, erythema migrans is a target-shaped rash that is sometimes a sign of Lyme disease. Erythema nodosum usually occurs in the legs, and involves the inflammation of fatty tissue under the skin. It’s characterised by one or more red bumps, and can be caused by an infection or certain autoimmune conditions.
If a rash also manifests as scaly skin, it’s often due to eczema. Other possible causes include fungal infections such as athlete’s foot and psoriasis (inflammation of the skin with plaques on the surface).
Macules and papules often form part of a rash. A macule is a small area of skin discolouration, while a papule is raised from the skin, often in a circular shape. Large patches of white macules can be an indication of a condition such as vitiligo, and a brown macule is usually a mole. Papules occur as a result of an insect bite or a condition such as acne.
Purpura and petechiae are potentially more serious. They are either dark red or purple patches, and require urgent treatment as they can indicate conditions such as meningococcal infection or even liver disease.
It’s also possible to experience nodules, blisters, and pustules with a skin rash. A nodule is an abnormal growth such as a wart, whereas a pustule is a blister that contains pus, such as a cold sore. Pustular psoriasis is an example of a condition where someone may develop a rash with pustules.
Diagnosing the cause of a rash
As there are so many potential causes of a rash, it can be difficult to diagnose a condition from an assessment of a rash alone, although some skin rashes have characteristics which make them easily identifiable.
A doctor will examine the rash. They will look for certain features, such as raised areas, lesions, plaques and distribution. Rashes can be highly concentrated in one area or evenly spread over the body, and can also affect the appearance of surrounding skin, potentially causing cracks and hardening.
For instance, contact dermatitis is often localised in one place where the contact with the allergen has been made. However, hives may be present if a more general allergic reaction has occurred. This causes red, raised bumps on the skin, sometimes all over the body.
After an examination, a doctor will ask several questions to find out more about patient history. They will look to establish how quickly the rash has formed, whether it is recurrent, where it started and how far it has spread, and if there are any other symptoms that accompany it.
They may seek to investigate possible triggers of the rash, such as starting a new course of medication, eating something that you have not eaten before, or being bitten by an insect. Sometimes underlying conditions can be a contributing factor in the development of skin symptoms.
Using this information, a doctor may have a good idea of what the cause of the rash is, but they may decide to conduct some tests to rule out other conditions. This may involve the use of blood tests, skin swabs to form a bacteria culture, and sometimes a skin biopsy so that a particular section of skin can be examined in more detail.
With meningitis, for example, the rash caused by the condition does not disappear when pressure is applied to it. If this rash is present, you may be referred for further tests to check what strain of the infection you have.
If you are concerned about a rash, you can contact one of our clinicians using our online video consultation service. Appointments are available between 9.30am and 4.30pm, Monday to Friday.
Treatment for a rash depends on what has triggered it, and its severity. If there is an underlying condition that a doctor suspects is the cause, this will need to be treated in order for the rash to clear up.
How is a rash treated?
Treatments for rashes are usually topical creams and ointments that can be applied directly on to the skin. Antihistamines and antibiotics can also be taken orally.
There are three areas that a doctor will focus on when recommending treatment: relieving the associated symptoms such as itchiness; protecting the skin from getting worse; and identifying the allergen if it is the cause.
Itching is very common for many rashes, and it’s important not to scratch them as this can exacerbate the rash. Scratching a rash can also cause it to spread to other parts of the body. Soothing the itchiness usually involves cooling the skin with an ice pack or an emollient. Camomile lotion is highly effective at providing relief from itching.
For more severe rashes caused by psoriasis, steroid creams can be effective as they penetrate the skin, but should not be used for an extended period. In conditions such as eczema and psoriasis where the skin can become dry and cracked, it’s important to use emollients and moisturisers to keep the skin hydrated, and stop it from becoming infected.
If a rash is triggered by an infection, a doctor will treat the infection causing it (with antibiotics if it’s caused by a bacterial infection, for example, or recommending plenty of rest if it’s triggered by a virus).
An allergy test may be recommended if your rash is thought to have been caused by an allergen. The two most common types of allergy tests that are conducted are patch tests, which involve putting a very small amount of the allergen on to the skin, and prick tests, which involve putting the suspected allergen into a cut in the skin.
How can a rash be prevented?
It’s difficult to prevent some types of rash, particularly if it is caused by a reaction to a medication or another condition.
However, there are some measures you can take to reduce your chances of developing a rash as a result of skin irritation. These include:
- avoiding very hot baths and showers, and using mild soaps, preferably unscented.
- allowing the skin to be exposed to fresh air, and keeping it dry and cool where possible.
- washing your hands after applying cream to a particular area to stop infection from spreading.
- refraining from wearing skin tight clothing as this can make sweating worse.
- patting the skin lightly with a towel when drying it, rather than rubbing it.
How long is it normal to have a rash for?
It largely depends on the cause. In many cases, rashes may disappear within a few days, especially if they’re caused by a viral infection.
However, some rashes are the result of a long term condition such as psoriasis, and may occur for days or weeks at a time during a flare-up.
Rashes caused by contact dermatitis may persist until the offending irritant has been removed.
Is a rash serious?
In most cases a rash isn’t serious, but it can in some instances reflect a more serious underlying condition which will need to be assessed by a doctor. You should seek urgent medical attention if the rash is accompanied by a fever or is showing signs of an infection.
Can I get treatment for a rash?
Yes. Treatment for a rash can often be acquired over-the-counter, if the rash is not a result of another condition. There are various different creams and ointments that can be used to treat rashes caused by conditions like eczema or psoriasis.
For more severe rashes, antibiotics and topical steroid creams may be necessary.
Your doctor will be able to discuss the different options with you after providing a diagnosis.
Can I speak to a doctor about a rash online?
Yes. Our online video consultation service allows you to speak to one of our GMC-registered clinicians about your rash. You can book an appointment between 9.30am and 4.30pm, and they can offer advice about how to manage the rash, and whether you may need further treatment. If suitable, our clinicians can also provide prescriptions, and referral to specialists, where required.