The Telltale Signs Your Rash Warrants a Trip to the Doctor

There is no one-size-fits-all way to identify the source of a rash, since this type of irritation can be caused by a number of different things.

Woman scratching patchy red skin on her arm.
Photo: Getty Images

Skin irritation is always a nuisance, and this is especially true of a rash, which most would describe as red splotches that itch. But rashes be caused by a number of different things, so they aren't always easy to pinpoint. "A rash is a non-specific term that describes a reaction that changes the color or texture of the skin; appears red, flaky, or bumpy; and feels itchy or potentially painful," says board-certified dermatologist at MDCS dermatology Marisa Garshick, MD. Oftentimes, people don't remember coming into contact with whatever irritated their skin. Instead, they're more likely to notice specific traumas, such as burns or scratches, adds Lynn McKinley-Grant, MD, a board-certified dermatologist and the advisor for skin care brand Namesake. So, how can you identify a true rash—and should you treat it yourself? Ahead, we asked Dr. Garshick and Dr. McKinley-Grant to share treatment tips and explain when it's time to give your doctor a call.

What causes a rash?

Rashes can be caused by a myriad of things. "Skin rashes can result from irritation of the skin, infections, autoimmune conditions, inflammation—as is the case with eczema or psoriasis— medications, allergens that may trigger contact dermatitis, or cancer," says Dr. Garshick. "They may also appear in association with other medical conditions, such as diabetes or thyroid disease." Rashes can happen anywhere on the body and differ in color and shape. If you want a real diagnosis and treatment plan, both experts say to check in with your dermatologist.

How can you tell if you have a rash?

Rashes can be categorized in many different ways, which explains why they often have varied symptoms—and according to Dr. Garshick, certain rashes don't have any signs at all. If you suspect you have a rash with symptoms, however, you are likely experiencing red marks that may be flat, raised, or bumpy, she notes. They can also be associated with flaking or scaling, and can often feel itchy; on the more extreme end, a rash can be painful, have bumps filled with pus, or result in blisters or crusting.

Other rashes, Dr. Garshick adds, may appear as discoloration. Some appear lighter or darker than your normal skin tone, while others take on a purple appearance; occasionally, rashes leave behind hypo- or hyperpigmentation when they fade. Longevity and frequency of this general condition can also vary: Some rashes come and go, while others persist. Dr. Garshick also points out that some iterations arise from a deeper layer of the skin; these lead to smooth lumps that do not prompt a color change.

Can you treat a rash at home?

Your treatment will depend on the specific cause of the rash, but Dr. Garshick notes that it is possible for rashes to be treated with topical steroid creams, such as hydrocortisone, or oral medications. For rashes associated with dry or irritated skin, she recommends a thicker ointment like Vaseline, which provides an occlusive barrier that locks in moisture. Rashes that itch benefit from anti-itch lotions, like the Sarna Original Anti-Itch Lotion ($29.95, or CeraVe Itch Relief Moisturizing Lotion ($13.49, Dr. McKinley-Grant adds that antihistamines, including Bendaryl, can also relieve the itch.

Rashes also worsen with sun exposure, which is why Dr. Garshick stresses the importance of wearing sunscreen and sun-protective clothing. Opt for a physical SPF that contains zinc oxide or titanium dioxide, since these formulas can be less irritating, she adds (she recommends something like the Skinceuticals Physical Fusion Defense Sunscreen ($36, or Blue Lizard Sensitive Mineral Sunscreen ($14.23,

You'll also want to steer clear of products that will increase irritation. "Really look at the products you are using," says Dr. McKinley-Grant, noting to identify both new formulas and ones you have been applying for a long time. "Take a break from these. Your skin may be reactive to the new products or has developed an allergy over time." In the interim, she recommends using fragrance-free soaps and lotions, avoiding hot showers, and being mindful of the clothes you wear (certain fabrics, like wool, can cause an adverse reaction).

When should you see a doctor?

According to Dr. Garshick and Dr. McKinley-Grant, the following symptoms indicate that you should absolutely seek medical attention for treatment, instead of waiting out the rash or attempting a DIY solution.

  • Blistering or open sores involving the eye, mouth, or genital area
  • Swelling (especially around the eyes or mouth)
  • Difficulty breathing
  • Fever
  • Night sweats
  • General fatigue
  • Pain
  • Rapid spreading of rash
  • Burning sensations
  • Deep itching

Regardless of whether or not you experience any of the extreme symptoms above, if you have any concerns about a rash, it's best to see a doctor. "Dermatologists are able to make a diagnosis by looking at the rash, prescribe patients a topical or oral medication, and even perform a biopsy and other key testing if needed," explains Dr. McKinley-Grant. "Some rash treatments also require biologic or phototherapy by a dermatologist." Being patient is also key: "Rashes can take time to heal, even with proper treatment," adds Dr. Garshick, "so it is important to be patient, but also to see a board-certified dermatologist for evaluation."

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