An injection site reaction is skin changes and irritation at the injection site. Such reactions may be especially common with some types of medication and in other cases may be the result of allergies or sensitivities. Some can be dangerous. If a patient notices skin changes, it is important to contact a doctor or nurse to discuss them. In some settings, nurses may monitor patients right after an injection for signs of a reaction due to concerns about a specific medication.
Such reactions are commonly divided into two basic categories: irritants and vesicants. When a patient has an injection site reaction to an irritant, the skin may become red and hot. It may flush, pucker, and develop hives or raised streaks. Some patients feel itching around the site and may experience discomfort. Rarely, a drug causes severe pain and distress.
Vesicants create blisters under the skin and can be dangerous. Many chemotherapy drugs have a vesicant action, requiring nurses to place IV lines very carefully for chemotherapy sessions to minimize leakage into surrounding tissue. In a blister reaction at the injection site, the skin inside the blister may die, and the patient may develop an open wound as the dead skin and tissue slough off. This can expose patients to the risk of serious infections.
Some medications are infamous for causing injection site reactions. Many patients, for example, experience irritation after vaccinations. The site around the injection will swell briefly before receding as the patient's immune system kicks into gear. Chemotherapy drugs and certain other strong drugs may also have a higher risk of reaction. Patients may need to wait a certain amount of time after receiving injections so nurses can see them, and patients are encouraged to speak up if they feel pain during an injection or infusion, or if they notice a skin problem afterward. .
Other patients may be more sensitive. Medicines may contain components such as gluten, aluminum, egg proteins, etc., which are used as fillers and vehicles for compounds in injection. Patients who have sensitivities and allergies to these ingredients are likely to experience an injection skin reaction. It is advisable for a patient to report any known sensitivity before receiving an injection. The doctor might select a different medicine to reduce the risk of a problem.
At other times, a patient may not be aware of an allergy. An injection site reaction could be the first warning sign that an allergy has developed, even if the patient has successfully taken the medication before. After an injection site reaction, a doctor may recommend some allergy tests to find out what the patient reacted to in order to avoid it in the future.