Determining whether a skin rash is simply a rash or an allergic reaction can be difficult, especially because a skin rash sometimes is the allergic reaction. Skin rashes caused by an allergen are usually localized, however. Hives are another major source of confusion when it comes to recognizing a skin rash from an allergic reaction, because they can look nearly identical and are often considered a type of skin rash. In addition, rashes on a baby’s diaper area are most often irritation caused by dampness. To be safe, have a health professional diagnose the rash to determine if it is something serious like a fungal infection.

A skin rash from an allergic reaction is often localized to the spot the allergen made contact. For example, if an oil you are allergic to made contact on your hand, that spot will develop the rash. The rash might be itchy and burn or sting when itched. A lot of other things can cause skin rashes too, so it is important to rule out poison ivy, infection, and other possibilities before determining that the rash is an allergic reaction.

Sometimes hives, one of the most common allergic reactions, are confused for rashes. Hives are red welts that itch and sometimes spread all over the body, combining with other hives. They can look very similar, to the point that even some doctors confuse them. One difference between hives and skin rashes is that hives do not develop blisters or ooze puss, though only some skin rashes progress this far.

Another common type of rash is called a diaper rash, and the location of the rash is a tell-tale sign of it not being a skin rash from an allergic reaction. It can affect both babies and adults who wear diapers on a regular basis. The rash usually appears on the buttocks, genital area or thighs, and can be treated with creams or powders. Keeping the area drier by changing wet diapers quicker can also help.

In general, rashes that quickly fade and disappear completely are nothing to worry about. A rash that covers a large portion of the body or one that lasts for days to weeks should be examined by a doctor. Sometimes redness and scaliness can be an indicator of a fungal infection. Such infections usually do not go away without the help of over-the-counter or prescription antibiotic creams, depending on the severity.