The skin is one of the most resistant organs in the body, but it still succumbs to irritants and infections that can cause red skin blotches. When they appear on the arm, the discoloration may be due to an allergic reaction, a chronic skin disorder or an infection. While most skin rashes are not life threatening, you should have the rash checked out by a doctor to make sure it is not related to a more serious condition that could cause medical complications.
Heat, fungus, parasites, bacteria and virus can cause red blotches to appear on your arm that may or may not respond to home remedies. Rosacea, psoriasis, atopic dermatitis, eczema and shingles can cause large red patches of skin to appear and become itchy and uncomfortable, according to Family Doctor. Hives, cellulitis and insect bites can create red splotches of skin that become irritated and painful. Other types of red skin blotches on your arm could indicate signs of skin cancer, measles, chicken pox or tinea infections.
Most red rashes itch and can become infected if you break open the skin while scratching. The skin inflammation may develop scabs or become crusty. Small white pustules on the red blotch may ooze pus or develop scabs, which may worsen when covered with the sleeves of your shirts. According to Medline Plus, the red sores may spread to other parts of your body or remain static.
While most red rashes that appear suddenly on your arm are a reaction to an irritant or the result of an injury, you should seek medical attention if the red blotch is accompanied by other symptoms. According to Medline Plus, if you become dizzy or short of breath, you should seek immediate medical care. Make arrangements to see your doctor if you have a fever or joint pain, if you've just started taking a new medication or if a red streak stretches out from the blotch. If the red area becomes hot or swollen, you also should get professional treatment.
Avoiding the irritants that caused the red rash is the first line of treatment for most cases of contact dermatitis and allergic outbreaks, according to the Mayo Clinic website. For example, if you are allergic to poison ivy, you should cover your arms and hands carefully before handling the toxic plant. You can apply cool compresses to a red itchy area of skin to relieve the discomfort of many forms of rash. Calamine lotion, antibiotic and anti-fungal prescription or over-the-counter creams applied to the rash may treat the rash effectively. Rashes that don't respond to initial treatment may require testing to determine the cause. According to Medline Plus, tests may include a biopsy, skin scrape, allergy testing or blood test.
In addition to avoiding substances that you know cause you to break out, you can make sure you and your children receive appropriate vaccinations. Regular hand washing can prevent the spread of bacteria and viral infections. Incorporating relaxation techniques such as yoga or meditation into your daily routine also may prevent breakouts. According to Medline Plus, stress can trigger rashes in people with chronic skin disorders.