Trigger point injections (TPIs) are shots delivered directly into painful muscle knots to break the cycle of pain and tightness. The knots, called myofascial trigger points, are small areas within a taut band of skeletal muscle that won’t relax on their own. They feel tender to the touch and often send pain radiating to other parts of the body. TPIs use a small needle, sometimes with a local anesthetic or other solution, to release the knot and restore normal muscle function.
What Trigger Points Actually Are
A trigger point forms when muscle fibers contract and then fail to release. The result is a tight, palpable knot that you or a provider can feel under the skin. These knots restrict blood flow to the area, starving the tissue of oxygen and energy while waste products build up. That combination creates a self-reinforcing loop: the muscle stays contracted because it lacks the energy to relax, and the ongoing contraction keeps blood from flowing in to deliver that energy.
Trigger points don’t just hurt where they form. Pressing on a knot in your upper shoulder, for example, can produce a headache or send pain down your arm. This “referred pain” pattern is one of the hallmarks providers look for during a physical exam. You might also notice stiffness, a deep ache, or a reduced range of motion in the affected area.
How the Injection Works
The needle itself does much of the work. When it penetrates the knotted muscle fiber, it causes the taut band to temporarily relax. That relaxation restores blood flow, allows the muscle’s energy stores to replenish, and clears out the metabolic waste that has been accumulating. The locked muscle fibers lengthen, and the pain-tension cycle breaks.
The injected solution adds another layer of relief. Most providers use a dilute local anesthetic such as lidocaine or bupivacaine, which numbs the area and reduces post-injection soreness. Some use a corticosteroid to calm inflammation, while others inject simple saline. In certain chronic cases, a form of botulinum toxin may be used to keep the muscle from re-tightening. A related technique called dry needling skips the liquid entirely and relies on the needle alone. A 2021 meta-analysis found that injections with a local anesthetic reduced neck pain intensity more than dry needling in the short term, though both approaches showed similar results for disability and range of motion.
Conditions TPIs Treat
The most common reason for a TPI is myofascial pain syndrome, a chronic condition defined by the presence of active trigger points. But the injections are used across a range of problems:
- Tension headaches and migraines caused by tight muscles in the neck and shoulders
- Fibromyalgia, where widespread muscle tenderness overlaps with trigger point pain
- Neck, back, and shoulder pain from poor posture, repetitive strain, or injury
- Sports injuries involving muscle overuse or strain
Your provider identifies the right injection site through a hands-on exam, pressing on the muscle to locate the knot and confirm that it reproduces your typical pain pattern. Sometimes a local twitch response, a brief involuntary jump of the muscle, confirms the spot.
What the Procedure Feels Like
The appointment is quick, often lasting only a few minutes for the actual injection. You’ll be positioned so the provider can easily access the affected muscle, whether that’s sitting upright for neck and shoulder work or lying face down for back injections. The provider cleans the skin, isolates the trigger point between their fingers, and inserts a thin needle directly into the knot.
You’ll likely feel a brief cramp or deep pressure as the needle enters the trigger point. Some people feel the muscle twitch, which is actually a good sign that the right spot has been reached. At each site, a small amount of solution (typically 0.2 to 0.5 mL) is injected after the provider confirms the needle isn’t in a blood vessel. Multiple trigger points can be treated in the same visit.
Recovery and Pain Relief Timeline
Most people experience some soreness at the injection site for the first day or two, similar to the feeling after a deep-tissue massage. Applying a heating pad for about 10 minutes at a time, four times a day, for the first few days helps ease that soreness. You can return to your normal exercise routine, but it’s best to avoid strenuous activity for a few days. Staying active and keeping the muscle moving is actually encouraged.
If you experience any weakness in the area after the injection, avoid driving for at least six hours. Pain relief typically begins within 24 to 72 hours and can last about a month. Some people need a series of injections spaced over several weeks to fully resolve a stubborn trigger point, while others get lasting relief from a single session. Physical therapy and stretching between sessions improve long-term outcomes by addressing the posture or movement patterns that created the trigger point in the first place.
Risks and Side Effects
TPIs are considered low-risk. The most common side effect is temporary soreness or bruising at the injection site. Minor bleeding can occur, especially if you take blood-thinning medications. Infection is possible any time a needle breaks the skin, though it’s rare with proper sterile technique.
The most serious complication, pneumothorax (a collapsed lung), is a concern only when injections target muscles near the ribcage, such as the upper back or chest wall. This is uncommon and largely preventable with proper needle technique and knowledge of anatomy. Allergic reactions to the injected anesthetic can also occur but are rare.
Cost and Insurance Coverage
Trigger point injections are almost always covered by insurance, according to the Hospital for Special Surgery. The main exception is when injections are performed too frequently, which typically signals an underlying issue that needs a different treatment approach. Ultrasound guidance, which is occasionally used to improve needle placement in deeper muscles, may not always be covered, though it’s rarely needed. Without insurance, a single session generally costs a few hundred dollars.