What are rashes?

A rash is a general term for an abnormal skin outbreak. When you have a rash, you know that something is wrong, even if you do not know exactly what it is that you are looking at. Some rashes are contagious, and others are not. Rashes can be itchy, painful, or cause a burning sensation on the skin. Causes vary widely, depending on the rash. For instance, a heat rash has an entirely different cause than skin rashes arising from contact with poison ivy.

What causes rashes?

There are many causes of rashes. Heat rash, common in hot weather, is caused by blocked sweat glands. Causes of skin rash include diseases, infections, allergic reactions, and insect bites.
woman itching

Types of rashes

Heat rash

Hot weather can bring about heat rash, which is caused by blocked sweat glands. Heat rash presents as reddened skin with tiny bumps or blisters, and feels itchy or “prickly.” It proliferates in areas of the body that are too hot, like skin folds in the groin, the armpit, or under the breasts. Dampness and poor air circulation also contribute to the problem. To treat and avoid heat rash, loose clothing should be worn in hot weather. Heat rashes are not dangerous, but they can be uncomfortable.

Rashes from poison ivy, oak, or sumac

These three plants found in nature contain urushiol oil, a substance that often triggers an allergy rash. These rashes present with itchy, large raised bumps, or blisters called vesicles. Each can require medical intervention if they cover extensive areas of the skin, or sensitive areas like the mouth or eyes. Poison sumac is usually the most severe. When you need care for a rash from poison ivy, oak, or poison sumac, visit FastMed.


Eczema, or dermatitis, is a chronic inflammatory condition thought to be caused by an overactive immune response. Eczema rash presents with large, raised, itchy, red areas that can appear dry and scaly. They occasionally ooze. At FastMed, we can treat simple eczema, dyshydrotic eczema, and other forms of contact dermatitis.


Psoriasis is a non-contagious autoimmune skin disease that speeds up the growth cycle of skin cells. Symptoms are patches of thick red skin and silvery scales. Psoriatic arthritis is an inflammatory type of arthritis with many of the same symptoms as psoriasis and arthritis.

Diaper rash

Diaper rash is a form of dermatitis that causes bright red skin on babies’ bottoms. Diaper rash has a variety of causes, such as a yeast infection, chafing from tight diapers, or prolonged exposure to urine or feces. It usually is not serious. However, if it does not go away after days of treatment, or is associated with other symptoms, such as fever, seek medical attention at FastMed.


Hives are generally caused by an allergic reaction, but they can be viral or autoimmune in nature, as well. They are primarily caused by the body’s immune response to something in the environment, and can also be caused by stress. Hives appear as very large, itchy, raised areas of the skin. When severe, they can become welts. Hives can flare up suddenly, and the reason is not always obvious.

Viral and bacterial rashes

Many diseases and illnesses can cause viral rashes, including measles, rubella, chickenpox, herpes simplex, and shingles, which is a reactivation of the chickenpox virus. Bacterial rashes include impetigo and meningitis when it is accompanied by a rash.

Viral and bacterial rashes can be symptoms of a serious illness. If you suspect a viral or bacterial rash, visit FastMed Urgent Care as soon as possible.

Fungal rash

Fungal infections can cause skin rashes. These include yeast infections, ringworm (tinea corporis), scalp ringworm (tinea capitis), athlete’s foot (tinea pedis), and jock itch. Fungal infections are usually not dangerous, just irritating. FastMed can diagnose and treat fungal infections.

Rashes from insects

The bites and stings of insects can cause rashes. Some examples are ticks, chiggers, mosquitoes, and bed bugs. Poisonous insects and insects that carry disease can also cause rashes. Serious tick-borne illnesses that cause rash include Rocky Mountain spotted fever and Lyme disease. The seriousness of the rash depends on the cause, but they all may require medical attention.

How to treat a rash

The proper rash treatment depends on the cause of the rash. Heat rashes will go away on their own, provided loose and light clothing is worn in hot weather. For other common rashes, there are many over-the-counter skin rash treatments. Common ointments include hydrocortisone and calamine lotion. Those can be found at the pharmacy. Allergic rashes, such as hives or poison ivy, may require the use of an oral antihistamine.

Rashes from insect bites may require special care and attention. The rash itself may not be serious, but other bite symptoms can be. In addition, bug bites may be a sign that your house is infested by insects. If you think you have been bitten by an insect, and you have symptoms such as a headache, a fever, or body aches, seek medical care at FastMed.

Skin rashes from illnesses can only be diagnosed by a qualified medical professional. Many skin rashes may be a sign of a serious condition. In addition, your healthcare provider should be able to recommend effective treatments and, if necessary, prescribe medications.

Where should you go to determine if your rash needs treatment?

When you have a skin rash, you want to start the healing process as soon as possible. Your primary care physician may not be able to see you right away, and only in very rare cases would the emergency room be the right choice for a rash. FastMed Urgent Care offers you the ideal solution.

At FastMed, our care providers are experienced in diagnosing and treating many of the above rashes and other common varieties, all without an appointment. We are open seven days a week, 365 days a year. You do not have to spend time worrying about a rash. FastMed will take care of it for you.

* The content presented on this page is not intended to diagnose health problems or take the place of professional medical care.