Pain after an injection is a common reaction. It's often a result of the needle itself or a response to the injected medicine, or both. This reaction can occur immediately or develop later.
Understanding Post-Injection Pain
The most frequent cause of pain after an injection is a localized reaction at the injection site. This is due to:
- Needle Trauma: The needle's puncture of the skin and underlying tissue causes minor inflammation and irritation.
- Medication Response: The injected substance can cause irritation or inflammation. This is a normal part of the body's response to a foreign substance. The immune system is triggered, causing the release of inflammatory chemicals leading to swelling, pain, and tenderness.
Different injections may lead to varying levels and types of pain. For example:
- Vaccines: Common side effects include soreness, tenderness, and mild swelling at the injection site, sometimes accompanied by fever, headache, and fatigue. Source: CDC - Possible Side Effects from Vaccines
- Epidurals: Although designed to relieve pain, epidurals can cause injection site pain as a side effect. Source: NHS - Epidural
- Intravitreal Injections: These injections, often used in ophthalmology, can lead to eye pain or discomfort as a side effect. Source: American Society of Retina Specialists - Intravitreal Injections
In rare instances, post-injection pain could indicate an infection at the site. Signs of infection include increased pain, swelling, redness, and warmth at the injection site. Source: Saint Luke's Health - Understanding Post-Injection Inflammation
When to Seek Medical Attention
While mild pain and swelling are normal, severe pain, or other symptoms like:
- Persistent, worsening pain
- Swelling that increases significantly
- Redness or warmth extending beyond the injection site
- Fever
- Pus or drainage from the injection site
- Allergic reactions (such as difficulty breathing, hives, or swelling of the face, lips, or tongue)
should prompt a call to your healthcare provider. Source: Verywell Health - When to Call Your Healthcare Provider About an Injection Side Effect
