Rashes are an extremely common medical presentation, particularly in children (RCHM 2018).
In fact, skin conditions, including rashes, are one of the most common presentations in general practice, accounting for 15.9 out of every 100 patient encounters in Australia (RACGP 2016).
Most rashes are temporary and aren't a cause for concern (HealthEngine 2017), and due to how common they are, may simply be brushed off as ‘nothing serious’.
However, rashes have a diverse range of potential causes and presentations, and in some cases require immediate medical attention (RCHM 2018).
Rashes can be difficult to identify, and as a healthcare professional, being able to recognise potentially dangerous rashes is critical.
So, how can common rashes be differentiated, and when is there a cause for serious concern?
This Article will provide an overview of some common rashes, along with related Ausmed resources. Please note that this is not an exhaustive list.
A rash is an area of skin that has undergone a change in texture or colour and may appear irritated or inflamed. It may be localised, or affect the whole body (NCI 2020).
Rashes can present in a variety of ways. The affected area skin might appear:
(NCI 2020; Soyer & Lee 2018)
Type: Acute, potentially life-threatening reaction.
Cause: Exposure to an allergen, typically a food, medicine or insect.
Rash appearance: Hives or welts - raised, bumpy, itchy rash that may be red or closer to the person’s normal skin colour. Swelling may be present, and the skin can feel hot or flushed.
Symptoms:
Other signs of anaphylaxis include:
Treatment: Immediate intramuscular adrenaline is required if the patient is experiencing shock, airway swelling or breathing difficulties. This should be followed by transportation to acute care where fluid and oxygen may be administered if required.
Note: In cases where anaphylaxis presents with skin-related symptoms only, adrenaline may not be required.
Further information: Recognising and Treating Acute Anaphylaxis
(ASCIA 2021; Ngan 2003; Queensland Health 2020)
Note: Specific management of bites and stings will depend on the causative insect.
Type: Acute reaction.
Cause: An insect penetrating the skin and potentially leaving its saliva, faeces or venom in the body.
Rash appearance: Often, a bite or sting will cause localised redness, with a bump or blister surrounding the puncture site. If the person experiences an allergic reaction to the bite/sting, there may be localised swelling, or in the case of a more generalised reaction, redness, swelling or hives in other areas of the body. In the case of an anaphylactic reaction, they may present with hives or welts.
Symptoms:
Treatment: Mild bites and stings will generally heal on their own within 48 hours. Techniques such as taking cool baths and showers, wearing loose clothing and applying topical lotions or creams may help to relieve itching.
Further information: Basic First-Aid for the Envenomated Person (Snakes, Spiders and Insects)
(Healthdirect 2021a; Better Health Channel 2017)
Type: Acute reaction.
Cause: Direct contact between the skin and an inflammation-causing stimulus. Common examples include nickel, chemicals, plants, cosmetics, perfumes and ointments. The rash generally occurs one to two days after the initial contact with the trigger.
Rash appearance: Cracked, red, blistered, thickened and dry skin, possibly with weeping.
Symptoms: Itching.
Treatment: The rash will gradually heal after the irritant is removed, within one to two weeks post-exposure. Symptoms may be treated with topical emollient moisturisers and steroid creams, or in the case of severe immune response, with oral medicines.
(Queensland Health 2020; ASCIA 2019; Soyer & Lee 2018)
Note: Healthcare workers are particularly susceptible to occupational contact dermatitis due to irritation from constant handwashing and the frequent use of gloves (Skin Health Institute 2021).
Type: Chronic condition.
Cause: The exact cause of the condition itself is unknown, but it may have a genetic component. Factors that may contribute to symptom flare-ups include:
Rash appearance: Scaly, dry, red patches of skin. The affected area may form tiny blisters filled with clear fluid and weep. Commonly affected areas of the body include the cheeks, elbow creases and backs of the knees.
Symptoms: Severe itching during flare-ups, with the affected areas potentially becoming infected.
Treatment: The condition can be managed by keeping the skin moisturised and protected, avoiding known irritants, and avoiding scratching. Flare-ups are generally treated using topical corticosteroids or calcineurin inhibitors.
Further information: Eczema
(Queensland Health 2020; ASCIA 2022; Better Health Channel 2020a)
Type: Acute viral infection, however, about 10% of people will experience chronic pain and tingling (post-herpetic neuralgia) for months or years after the infection.
Cause: Reactivation of the dormant varicella-zoster virus in people who have previously had chickenpox.
Rash appearance: Red rash with fluid-filled blisters that break open and crust over. The rash is typically only on one side of the body, on the face, chest, back, abdomen or pelvis.
Symptoms: On the affected area of the body, the person will initially experience pain, a burning, tingling, itching or stabbing sensation, sensitivity to touch, and numbness, as well as other symptoms like sensitivity to light, fatigue, fever and/or headaches. Two to three days after the onset of these symptoms, a rash will appear in the affected area.
Treatment: Shingles resolves on its own within two to six weeks. However, prescription antiviral medicines can be used to reduce the severity of symptoms and the risk of complications. Taking over-the-counter analgesics, keeping the rash dry and clean, avoiding scratching and wearing loose clothing may also assist in symptom management.
Further information: What Causes Shingles (Herpes Zoster)?
(Mayo Clinic 2021; Healthdirect 2021b)
Type: Chronic inflammatory condition.
Cause: Skin cells growing too quickly. The exact cause of the condition is unknown, but it may have a genetic component. Factors such as smoking, excessive alcohol consumption, certain medicines, sun exposure, injury and certain infections (e.g. streptococcal tonsillitis) can exacerbate symptoms.
Rash appearance: Red, dry, plaques covered with silvery scales. The plaques have clearly defined borders. The rash can appear on any part of the body, but most commonly affects the knees, elbows, lower back and scalp. Rarer types of psoriasis may cause pus-filled blisters or a red, peeling rash. Plaques that have cleared often leave brown or pale marks that gradually fade.
Symptoms: Itching is mild in most patients, but can be severe. Scratching may cause skin thickening, and the patient may also experience painful skin cracks or fissures.
Treatment: Depending on the severity, symptoms may be managed using topical therapy, phototherapy, systemic therapy or targeted therapy. Symptoms can also be improved by avoiding smoking and reducing alcohol intake.
(Healthdirect 2021c; Oakley 2014)
Type: Chronic condition.
Cause: Unknown, but is thought to be related to genetic, environmental, vascular, and inflammatory factors. Symptoms may be exacerbated by factors such as stress, alcohol, heat, exercise and spicy foods.
Rash appearance: Persistent redness and flushing that only affects the face, accompanied by enlarged capillaries. The rash may resemble a sunburn. In some cases, there might also be pimples on the forehead, cheeks and chin.
Symptoms:
Symptoms typically worsen with age and might include:
Treatment: Symptoms can be managed by avoiding known triggers, applying creams and gels, using a diathermy to apply heat to damaged blood vessels and undergoing laser surgery to treat enlarged capillaries.
(Better Health Channel 2020b; Queensland Health 2020)
Type: Acute parasitic infection.
Cause: Infestation by Sarcoptes scabiei mites, which burrow under the skin and lay eggs. Scabies can be spread between people via direct contact.
Rash appearance: Small red bumps that often form a line and may resemble hives, bites, knots or pimples. Sometimes the rash resembles scaly eczema patches. There may also be visible burrows on the affected areas. Commonly affected areas of the body include the wrists, fingers, armpits, elbows, buttocks and groin.
Symptoms: Intense itching that worsens at night and after hot baths and showers. Scratching may lead to infection.
Treatment: First-line treatment is generally the application of 5% permethrin cream or lotion. This is an insecticide used to kill parasites.
(Better Health Channel 2020c; AAD n.d.; Stewart 2021)
Type: Acute bacterial infection.
Cause: Infection by group A streptococci bacteria, which is the same bacteria that causes strep throat, impetigo and rheumatic fever. The bacteria is spread by coughing, sneezing, or making contact with an infected person or contaminated surface. It predominantly affects children between the ages of 5 and 15.
Rash appearance: The rash initially presents as red blotches, which most commonly appear on the face, neck, underarms or groin. Within 24 hours, the rash spreads to the rest of the body and changes to resemble a sunburn, with a sandpaper-like texture. Three to seven days later, the rash will peel.
Symptoms:
Treatment: Antibiotics must be administered to prevent the bacteria from spreading and potentially causing serious complications like rheumatic fever, kidney disease, pneumonia or arthritis. Rest, pain relief and adequate hydration may assist in symptom management.
Further information: All About Strep Throat
(Healthdirect 2021d; Oakley 2015)
Type: Acute viral infection.
Cause: Infection with the varicella-zoster virus, which is spread through inhaling the particles dispersed when an infected person coughs or sneezes, or through touching the fluid from an infected person’s chickenpox blisters.
Rash appearance: Red rash that turns into fluid-filled blisters, which may then burst and crust over.
Symptoms:
Treatment: Chickenpox is generally mild and will resolve on its own. Symptoms can be managed by resting, avoiding scratching, taking lukewarm baths with baking soda or oatmeal, taking paracetamol and using creams or lotions to decrease itching.
(DoH 2022; Healthdirect 2021e)
While some rashes are mild and don’t have any cause for concern, the following signs may indicate a serious illness and should be escalated immediately:
(Barrell & Bard 2021; HealthONE 2020; AAD 2015; Donaldson 2020; HealthEngine 2017)
Question 1 of 3
Which one of the following rashes is acute?
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