Either way, finding a mysterious red, itchy or scaly patch on your body can be alarming, as it's often unclear if it can be relieved with an over-the-counter salve or if it needs more serious medical attention.
A rash is defined as an area of irritated or swollen skin that can cause changes in texture or colour and inflammation. Many rashes are itchy, red, painful, and irritated, and they can be a result of an infection, a chronic skin condition or an allergic reaction.
If you find an unexplained red patch on your body, it's important to speak to a doctor, as they will be able to diagnose what kind of rash you have and decide how urgently you need treatment.
We spoke to Dr Naveen Puri, lead physician at Bupa Health Clinics to identify some of the most common skin rashes and what causes them.
Chickenpox is a highly contagious infection that causes an itchy, spotty rash.
"The spots are called 'vesicles', which often look like individual bubbles filled with pus, that will quickly burst and then scab over," explains Puri.
"We usually get chickenpox as a child, but adults can get it too, and the red pocks often go away after a week or two."
An important rule of thumb is to seek help if a rash came with other symptoms, and Puri adds that telltale chickenpox marks are often accompanied by high temperature, aches, pains and loss of appetite.
"Cooling gels and taking paracetamol can help with itching, but you should seek help from your GP if the chickenpox gets worse, or if the skin around the blisters is hot or painful."
Shingles is a viral infection which causes a painful rash near one or more nerves.
"This makes the skin very sensitive," notes Puri. "It will usually start as a reddened or purple patch and quickly develop into clusters of fluid-filled sacs."
Puri explains that they look similar to chickenpox and are caused by the same virus, but appear in clusters rather than as separate spots.
"Some people describe it as looking like small 'bubble wrap'," he adds. "After the vesicles burst, they will crust over into blisters that weep fluid before scabbing over."
Shingles usually affects the skin but can also affect the eyes. "You should contact your GP if you suspect you might have shingles as they can give you medication to help with recovery," says Puri.
In some cases, it is important that you see a GP as soon as possible, especially if: the rash is widespread and painful; you have pain and a rash develops near your eye; you're over 60 or someone in your family has a weakened immune system.
"Hives usually appear as a reddened, itchy, raised rash in small patches," says Puri, who notes that it's often caused by a reaction to certain foods, pollen, animal fur or hair, or insect bites.
Hives usually settle quite quickly and antihistamines can be taken to help bring them down too.
Puri says that hives will often resolve themselves without medical intervention, but you should speak to your doctor if they haven't settled within two days, if the rash appears to be spreading, the hives keep coming back, you have a high temperature, you feel unwell or have swelling under the skin.
Psoriasis is a condition which causes red, itchy, flaky, scaly patches that are commonly found on knees, elbows and the scalp. It can also sometimes cause small pin-point dips called 'pitting' in your nails,
"Psoriasis is a long-term condition and tends to come and go in cycles," advises Puri. For instance, you might get a flare-up that can last a few weeks when things are stressful, or you might go for months without any symptoms.
Your GP can help you to manage the condition, and they can also recommend over-the-counter creams and ointments to help ease the discomfort. If your psoriasis is severe though, Puri says your doctor may refer you to a dermatologist for additional care.
Eczema is a common term for a group of conditions that make your skin inflamed or irritated.
"Atopic dermatitis is the most common form of eczema, and it causes the skin to become itchy, dry, and cracked in severe cases," says Puri.
"It can affect people in different places, such as the hands or behind the knees or in patches across larger areas of the body."
There's currently no cure and severe eczema can have a significant impact on daily life. Soap substitutes, creams and steroid preparations can help to relieve the painful symptoms, as well as self-care techniques, such as reducing scratching and avoiding triggers.
Rosacea is one of the easiest rashes to spot. It's characterised by a redness that appears as if you are blushing, with blood vessels showing on your face - most typically around the inner cheeks by the nose, across the nose, and forehead.
"It can also produce small, red, pus-filled bumps," says Puri. "This can often be mistaken for acne, as symptoms may flare up for a couple of weeks and then disappear.
"It can be triggered from alcohol, spicy food, caffeine, cheese, stress, and even exercises such as running."
Puri recommends keeping a skin diary so you can identify any potential triggers, and to speak to your GP, who will be able to prescribe treatments such as creams and gels for your skin, or antibiotics.
And remember: Although most rashes are not life-threatening, some rashes can signal something more serious. It's important to seek medical attention if your rash is spreading quickly, has other symptoms, begins to blister or is painful to touch.