Trigger point injections (TPIs) are a common treatment used to address myofascial pain, which stems from hypersensitive knots in muscle tissue known as trigger points. These injections typically involve a local anesthetic, such as lidocaine, often combined with a corticosteroid, delivered directly into the taut muscle band. The goal is to relax the muscle, break the pain-spasm cycle, and provide relief that can last for weeks or months. Addressing concerns about increased discomfort requires understanding the normal, temporary effects of the injection versus signs of a true complication.
The Expected Post-Injection Soreness
A temporary increase in pain is a common and predictable side effect of a trigger point injection. The primary mechanism for this soreness is the mechanical irritation caused by the needle passing through the tissue and the physical disruption of the muscle knot. This action, sometimes described as microtrauma, is necessary to deactivate the trigger point.
The injected solution, even if it is just saline or local anesthetic, adds volume and pressure to the already sensitive muscle, contributing to the feeling of muscle ache. This sensation is often described as feeling like a deep bruise or a low-grade muscle strain in the injected area. This post-injection soreness typically peaks within the first 24 to 48 hours following the procedure. If only an anesthetic was used, some patients may feel immediate relief until the numbing agent wears off, at which point the expected soreness begins.
Differentiating Normal Discomfort from Complications
Managing anxiety after a TPI requires recognizing the difference between normal, temporary soreness and symptoms that indicate a problem. Normal discomfort remains localized to the injection site, feeling like a dull ache or bruise, and should steadily improve after the first two days. Conversely, pain that persists beyond 72 hours without any sign of improvement, or pain that actively worsens after the initial 48-hour window, warrants attention.
The type of pain is also a major differentiator; normal soreness is an ache, while sharp, shooting, or intense pain that radiates down a limb may suggest nerve irritation. While nerve injury is extremely rare, a sudden, severe increase in pain, numbness, or weakness immediately following the injection should be noted. Furthermore, the presence of associated symptoms is a red flag, as expected soreness should not cause systemic illness. Signs of a potential infection include fever, chills, or a spreading area of redness, warmth, or pus at the injection site, which extends significantly beyond the small puncture mark. Difficulty breathing is an extremely rare but severe complication, particularly with injections in the upper back or neck, and requires immediate medical attention.
Factors Influencing the Pain Response
The intensity and duration of the pain response can vary widely among patients due to several factors related to the injectate and the technique. When corticosteroids are included, a “post-injection flare” can occur, causing a temporary, acute increase in pain and inflammation. This flare is thought to be caused by a transient inflammatory reaction to the steroid crystals within the solution. Approximately 20% of patients who receive a corticosteroid injection experience this flare, which can delay the onset of relief by a couple of days.
The precision of the injection technique also plays a role in the immediate pain experienced. If the needle misses the exact center of the trigger point or inadvertently irritates a small, localized nerve bundle, the pain can be more pronounced than average. Additionally, individual patient characteristics, such as an existing underlying inflammatory condition or a lower personal pain tolerance, can amplify the perception of the post-procedure soreness.
When to Contact Your Healthcare Provider
Contacting your healthcare provider is important for ensuring a safe recovery. Any signs of infection, such as fever, chills, or persistent, spreading redness and warmth at the injection site, require an immediate call. Similarly, if you develop new or worsening neurological symptoms, including significant numbness, tingling, or muscle weakness that was not present before the procedure, you should seek medical guidance.
Pain that is so severe it prevents sleep or is not managed by over-the-counter medication after 48 hours should also be discussed with your provider. For routine post-injection soreness, patients are typically advised to rest the area and avoid strenuous activity for a few days. Applying ice or heat, as specifically directed by your clinic, and using acetaminophen or ibuprofen can help manage the expected mild discomfort while the body recovers.