Which infectious conditions cause red spots?

A variety of conditions can cause red spots, such as infectious and allergic.
A variety of conditions can cause red spots, such as infectious and allergic.

Some of the common infections that cause red spots include:

  • Fungal infections like ringworm: A ringworm looks like a ring of red spots that surrounds a clear area. Treatment involves anti-fungal ointments and medications.
  • Shingles: They are medically known as herpes zoster. Shingles is a painful rash that can present with blisters that are formed on one side of the face or body. Since it is a viral rash, it is treated by anti-viral oral pills.
  • Roseola infantum: Roseola infantum is a viral infection that occurs in babies and causes a high fever followed by a rash. There is no specific treatment for roseola infantum. Most cases of roseola infantum are mild and self-limited. Treatment involves rest, adequate fluid intake, and medications to control the fever.
  • Erythema infectiosum or Fifth disease: A viral infection that commonly occurs during childhood. Signs and symptoms include a red rash on the cheeks that resemble a slapped cheek, fever, sore throat, stomach upset, and headache. Generally, no treatment for the Fifth disease is necessary. An antihistamine can be used if the rash is itchy.
  • Viral diseases, such as measles, rubella, chickenpox, and COVID-19: Each of these conditions is associated with its own signs and symptoms. It is advisable to contact a doctor for the correct diagnosis and treatment.

Which allergic conditions cause red spots?

Some of the common allergic conditions with red spots are:

  • Contact dermatitis: Allergy to latex, an insect (mosquitoes, ticks) bite, and diapers (diaper rash in children) are examples of contact dermatitis. Treatment involves the use of oral pills of antihistamines and creams for local applications to relieve the itch, such as a calamine lotion or moisturizer mixed with a steroid (hydrocortisone).
  • Food allergies: People may have an allergy to certain foods, which can appear as rashes. The most common foods are fish, shellfish, peanuts, and tree nuts like walnuts. Problem foods for children can include eggs, milk, peanuts, soy, and wheat.
  • Drug rash: A sudden allergic reaction to any medicine can appear in the form of a rash. It is advisable to contact the doctor who will consider your medical history and prescribe an alternate medicine.
  • Atopic dermatitis: It often starts in babies and can either go away with age or stay permanently with flares throughout life. Atopic dermatitis treatment is aimed at managing flares and keeping the skin moisturized.
  • Poison ivy, poison oak, or poison sumac rash: Touching any of these plants results in blistering red spots with intense itching all over the body in most people. The red spots usually subside on their own within 7 to 21 days. Treatment includes washing the affected part with lukewarm or soapy water, applying Calamine lotion, and taking antihistamine medications to relieve the itch.


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What are the other conditions that cause red spots?

The other common conditions that cause red spots but not because of any allergy or infection include:

Heat rash: Red spots caused by over-exposure to the sun or heat are known as heat rash. Treatment involves applying a soothing lotion, such as Calamine lotion or aloe vera. Preventive measures include applying sunscreen lotion before venturing out and wearing full sleeve tops.

Swimmer itch: Swimmer itch is a rash that comes from being in the water where certain infected snails are present. It normally subsides on its own in about a week and medical treatment is generally not needed.

Acne rosacea: A chronic skin condition in which a red rash appears most commonly on the cheeks and around the nose. The disease is characterized by flares that are triggered by a variety of factors. A doctor will be able to suggest the most effective treatments.

Pityriasis rosea: A scaly reddish-pink rash that sweeps outward like the branches of a pine tree. It commonly appears mostly on the chest, abdomen, and back and is most common in people between 10 to 35 years of age. Treatment includes antihistamine pills.

Psoriasis: Psoriasis appears as silvery or red, scaly, itchy rashes, most commonly over the knee joints, elbows, fingers, and toes. There are several types of psoriasis and each appears slightly different than the other. Treatments involve the application of creams and medications to the skin, light therapy, and injectable medications.

Petechiae: These are red spots that appear due to the rupture of tiny blood vessels (capillaries) under the skin. These may happen in:

If the red spots cause severe discomfort and are associated with fever or unusual signs, it is vital to consult a doctor who can diagnose the condition and start the treatment immediately.

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Medically Reviewed on 9/29/2020
Allmon A, et al. Common Skin Rashes in Children. Am Fam Physician. 2015;92(3):211-216.

Petechiae. Available at: https://www.mayoclinic.org/symptoms/petechiae/basics/causes/sym-20050724

Slide show: Common skin rashes. Available at: https://www.mayoclinic.org/skin-rash/sls-20077087