Allergic reactions on skin

Allergies don’t just make you sneeze. They can show up as hives or rashes too. Insect bites or stings can also cause allergic reactions. Many rashes or cases of hives are harmless, but if you are worried about a skin reaction, especially if it is accompanied by other symptoms, see your doctor.*

Here is a primer on common allergic reactions on skin:

*Seek medical attention immediately if you are experiencing a life-threatening anaphylactic reaction, as BENADRYL® is not indicated for such use.


Hives are a common allergic reaction caused by the release of histamine and other chemicals into your bloodstream. (Also known as urticaria.)

APPEARANCE: Itchy, red or skin-coloured welts that come and go over several days (unlike chicken pox or insect bites). When you press the center, they turn white. Can range in size from a small dot to several centimetres in diameter and can join together. They do not usually leave a lasting mark.

TREATMENT: Use BENADRYL® Itch Cream or BENADRYL® Itch Spray.

If hives are widespread, using oral BENADRYL® products can also help relieve the swelling and itching (and therefore help prevent scratching).

TIP: Avoid hot baths or showers and tight clothing during or just after an episode of hives.

CALL THE DOCTOR IF: You have a severe reaction with swelling of the throat.


APPEARANCE: Rashes may or may not include these symptoms:

  • redness
  • itchiness
  • swelling or bumps
  • oozing or blisters
  • flaking or scaling


CAUSES: Many things can cause rashes, such as an allergic reaction (including a reaction to medication), infection, or overheating.

Also, if an irritant comes in direct contact with skin, it can cause contact dermatitis, a red, very itchy or burning area, sometimes with blisters. It can take 24 or 48 hours to show up. Plus, the reaction might not happen after the first contact, but after repeated exposure, such as using the same lotion or detergent many times.

Common causes of allergic contact dermatitis: Poison ivy or oak, metals (such as nickel in jewelry), rubber or latex, cosmetics, and detergents.

TREATMENT: Gently clean the rash area with mild soap and water to remove the irritant. To relieve the itch, use BENADRYL® Itch Cream or BENADRYL® Itch Spray.

Oral BENADRYL® products will also help relieve itching (and therefore help prevent scratching).

TIP: Cool, wet compresses can sooth the itch.

CALL THE DOCTOR IF: The rash is severe, is accompanied by other symptoms, gets worse quickly or doesn’t subside within a week.

Insect bites

When an insect bites or stings, your immune system reacts to the insect’s venom or other substance, causing redness, swelling, itching, or pain.

APPEARANCE: Bites from mosquitoes, ticks, spiders, and black flies can cause redness, swelling and itching. Some can also cause tenderness and blistering. These symptoms usually disappear slowly over a few days.

TREATMENT: Apply BENADRYL® Bug Bite Relief for fast, effective relief of itchiness and pain from insect bites and stings. It has a topical antihistamine/analgesic and a skin protectant to give you triple action relief that relieves itch, soothes pain, and protects skin.

Oral BENADRYL® products will also help relieve swelling and itching (and therefore help prevent scratching).

TIP: : Keep the bite area and fingernails clean to avoid infection from scratching. Try pushing on a bite instead of scratching, or use cold compresses.

CALL THE DOCTOR IF: You develop hives, face or throat swelling, or difficulty breathing (seek urgent care). If swelling, redness or pain around the bite gets worse after the initial reaction, you might have an infection. Also watch for nausea, vomiting, chills, fever, cramps, muscle aches, dizziness, confusion or weakness after an insect bite.

Mosquitoes can carry West Nile virus and malaria (in some countries) and ticks can carry Lyme disease. Check with your doctor if you develop unusual symptoms such as fever, joint pains or rash after an insect bite.