The appearance of an allergic reaction and viral rash is often similar, but the cause of these rashes is entirely different 3. A rash is rarely serious, but sometimes it can indicate an underlying illness that requires treatment. If you or your child has an unexplained rash, consult your doctor for an accurate diagnosis.
If you are experiencing serious medical symptoms, seek emergency treatment immediately.
Hives are an allergic reaction characterized by red raised bumps that range in size. These bumps are itchy and can appear anywhere on the body. Small hives can merge together and create large swollen dry areas of skin or the bumps can migrate from one area of the body to another. Severe allergic reactions can cause open sores to appear. Rashes caused by an allergic reaction usually appear within 48 hours after being exposed to an allergen. A drug rash can cover large area of the body. A rash caused by viral illnesses, however, develops as the person starts feeling better. These rashes may or may not itch.
- Hives are an allergic reaction characterized by red raised bumps that range in size.
- These bumps are itchy and can appear anywhere on the body.
Human Skin Rashes From Dogs & Cats
An allergic reaction is caused by your immune system overreacting to a substance known as an allergen. During the initial contact with an allergen, your body begins producing antibodies to fight the foreign substance. The next time you come in contact with the allergen, chemicals such as histamines are released by your immune system and trigger hives. Common causes of hives are poison ivy, medications, rubber, detergents, fragrances and latex.cause:
- Common causes of hives are poison ivy
There are several types of viruses that cause rashes: roseola, which is caused by the human herpes virus 6; chickenpox, which is caused by the varicella zoster virus; and fifth disease, which is caused by human parvovirus B19. Other viruses that cause rashes are the coxsackie virus and rubeola virus.
- An allergic reaction is caused by your immune system overreacting to a substance known as an allergen.
- The next time you come in contact with the allergen, chemicals such as histamines are released by your immune system and trigger hives.
A rash caused by an allergy is treated with oral antihistamines. Acute hives can last a few minutes to a few weeks. If hives are severe, an oral corticosteroid may be needed to reduce inflammation of the skin. If a medicine causes the rash, it takes a few days to a few weeks after stopping the medication for the allergic reaction to disappear. If your airways are swelling from an allergic reaction, seek immediate medical attention.
There is no treatment for viruses, but you can relieve itchiness of related rashes with antihistamines or cool compresses. If you have a fever or the rash is painful, acetaminophen or ibuprofen can provide relief. Antibiotics are only effective at treating secondary bacterial infections caused by scratching itchy rashes; they do not speed the healing process for a viral illness 3.
- A rash caused by an allergy is treated with oral antihistamines.
- There is no treatment for viruses, but you can relieve itchiness of related rashes with antihistamines or cool compresses.
Causes of a Full Body Rash
Once you’re aware of an allergen, avoid it. Unlike respiratory allergy sufferers, someone with allergic contact dermatitis can usually avoid contact with triggers 4. If you touch an allergen, immediately wash the area with soap and water. If you’re in a grassy area, dress in clothes that cover your skin and stay in the middle of cleared paths as often as possible. Always keep track of medications that have caused an allergic reaction in the past. Use detergents that are free of fragrances and irritating chemicals. If you’re unsure of the cause of your allergy, consult an allergist. There are vaccinations for measles and chickenpox, which prevent these viral illnesses. Wash your hands frequently, especially after using the restroom and before eating. Avoid close contact with people who appear ill.
- Once you’re aware of an allergen, avoid it.
- If you touch an allergen, immediately wash the area with soap and water.
Human Skin Rashes From Dogs & Cats
Causes of a Full Body Rash
Difference Between Hives & Shingles
Rash on My Arms After Exercise
How to Get Rid of an Allergic Reaction Rash
How to Treat a Rash From a Dog Scratch
Antihistamines & Itchy Skin With No Rash
Bronchitis Symptoms With Allergies
Allergic Reactions With Skin Blotches
Skin Rashes on Legs Following Exercise
- American Academy of Allergy, Asthma & Immunology: Skin Allergy
- MayoClinic.com: Slide Show: Common Skin Rashes
- The Kid’s Doctor: Viral Skin Rashes
- PubMed Health: Contact Dermatitis
- Schaefer P. Acute and Chronic Urticaria: Evaluation and Treatment. Am Fam Physician. 2017 Jun 1;95(11):717-724.
- Handa S, De D, Mahajan R. Airborne contact dermatitis—Current perspectives in etiopathogenesis and management. Indian J Dermatol. 2011 Nov-Dec; 56(6): 700–706. doi:10.4103/0019-5154.91832
- Hives. MedlinePlus. U.S. National Library of Medicine. Updated May 2, 2017.
- Cabanillas B, Brehler AC, Novak N. Atopic dermatitis phenotypes and the need for personalized medicine. Curr Opin Allergy Clin Immunol. 2017 Aug;17(4):309-315. doi:10.1097/ACI.0000000000000376
- Jenerowicz D, Silny W, Dańczak-Pazdrowska A, Polańska A, Osmola-Mańkowska A, Olek-Hrab K. Environmental factors and allergic diseases. Ann Agric Environ Med. 2012;19(3):475-81.
- Mowad CM, Anderson B, Scheinman P, Pootongkam S, Nedorost S, Brod B. Allergic contact dermatitis: Patient management and education. J Am Acad Dermatol. 2016 Jun;74(6):1043-54. doi:10.1016/j.jaad.2015.02.1144
- Wallach D, Taïeb A. Atopic dermatitis/atopic eczema. Chem Immunol Allergy. 2104;100:81-96. doi:10.1159/000358606
Melissa McNamara is a certified personal trainer who holds a Bachelor of Arts in journalism and communication studies from the University of Iowa. She writes for various health and fitness publications while working toward a Bachelor of Science in nursing.