The Difference Between Allergic and Injection Site Reactions

This handout will explain the difference between allergic and injection site reactions from getting a shot. Know the difference so you can avoid delays in treatment and use the medicine safely.

Injection Site Reaction

All medicines given as a shot may cause a local reaction. Local refers to side effects only at the site of the shot. These include: redness, itching, pain, swelling, bruising, burning, or a small amount of bleeding. Site reactions are usually mild and go away within one to three days.

To Reduce Your Chance of a Reaction

•Let the medicine sit at room temperature for up to 30 minutes before use. This helps reduce pain.
•Give diphenhydramine (Benadryl)30 minutes before.
•Apply hydrocortisone cream after tohelp with itching, redness, andswelling. A pain reliever may also beused. Talk with your clinic to findone right for you.
•Allow the skin to dry after using thealcohol swab. If not dry, alcoholpushed in by the needle can causeburning.
•A cold pack applied to the site beforeand after may help to numb the area.Do not use a warm compress orheating pad as this will increaseblood flow and may cause morepain.
•Make sure the shot is given in fattyareas by pinching the skin. A shot ina muscle hurts more than in fat.
•Change spots where the shot is given.
•Never give a shot in a bruise, scar, visible vein or areas with redness, swelling, or broken skin.
•Write down site reactions including all side effects and what you did to help them. Bring your notes to your next clinic visit.

When to Call

Call the clinic if:
•Reaction does not go away after 3days.
•The local reaction is severe. Severe means: blisters, redness that is larger than your fist (more than 2 inches across), severe bruising, bleeding, pain or itching.
•Site reactions seem to be gettingworse with each shot.
•You have a rash across the bridge of your nose and cheeks.
•You see purplish-red spots anywhere on your body.

Call 911 if you have:
•Swelling of the face, lips or tongue
•Throat swelling or trouble breathing
•Chest tightness
•Hives

Who to Call

Call your health care team at the Digestive Health Center: 608-890-5000