A trigger point is a painful area in a muscle. It may feel like there is “knot” in the muscle or an area of tightness. When pressure is applied to the trigger point, the pain spreads out to other areas of the body.

A trigger point injection is a shot that is given in this painful spot.

  • Thigh Muscles

    Posterior Thigh Muscles

    If you have a trigger point in the thigh muscle, the doctor can give an injection to relieve pain.

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  • Reasons for the Procedure

    Trigger point injections are given to reduce pain and increase physical functioning so that you can participate in a physical therapy program.

    Possible Complications

    Complications are rare. But, no procedure is completely free of risk. If you are planning to have this injection, your doctor will review a list of possible complications, which may include:

  • Tenderness, bruising, or bleeding at the injection site
  • Infection
  • Dizziness
  • Allergic reaction to the local anesthetic or medicine
  • Damage to organs, such as the lung (rare)
  • The need for other treatments if this injection is not effective
  • Factors that may increase the risk of complications include:

  • Smoking
  • You should not have this injection if you:

  • Have allergies to the local anesthetic or medicines being used
  • Have a current infection
  • Have a bleeding disorder
  • Are pregnant
  • What to Expect

    Prior to the Procedure

    Your doctor may:

  • Do a physical exam and ask you about your medical history
  • Have tests done (eg, x-rays , MRI scan )
  • Ask you about any allergies that you may have to the anesthetic, pain medicine, or latex
  • Talk to your doctor about your medicines. You may have to stop taking some medicines up to one week before the procedure, like:

  • Aspirin and other nonsteroidal anti-inflammatory drugs (eg, ibuprofen , naproxen )
  • Blood-thinning drugs, such as warfarin
  • Anti-platelet drugs, such as clopidogrel
  • Depending on where your trigger point is, you may need someone to drive you home after the procedure.


    You will typically remain awake during the procedure. A local anesthetic may be used to numb the area where the injection will be given.

    Description of the Procedure

    First, the skin around the painful area will be cleansed with an antiseptic. Next, the doctor will locate the trigger point. This may be done by feeling for the painful area with his fingers. Once the trigger point in found, a thin needle containing medicine will be injected. The injection may contain a long-acting pain reliever, a water solution, or a corticosteroid to reduce inflammation. Botulinum toxin is also sometimes used for trigger point injections associated with muscle contraction. Sometimes the doctor will simply put the needle into the trigger point and not inject any medicine. This is all done to break the pain cycle at the trigger point. If you have more than one trigger point, you may need several injections.

    Some doctors may use needle-guided electromyography (EMG) to locate the trigger point. With this approach, a needle will send information to a monitor, which will allow the doctor to make sure he has located the right spot.

    How Long Will It Take?

    The injection takes a few minutes.

    Will It Hurt?

    When the doctor feels for the trigger point, you will have discomfort. You will also feel a pinching sensation when the needle goes through your skin. You may have pain, which should not last long.

    Post Procedure Care

    At the Care Center

    The hospital staff will apply pressure to the injection site and place a bandage there. You will be observed for a short time to make sure you do not have any poor reactions to the injection. Then, you will be able to go home or return to work.

    At Home 

    Take these steps to help ensure a smooth recovery:

  • To reduce soreness, apply ice or a cold pack to the affected area for 15-20 minutes, four times a day. You may want to do this for several days. Wrap the ice in a towel. Do not apply it directly to your skin.
  • Take over-the-counter pain medicine as recommended by your doctor. The soreness should go away in a couple of days.
  • Follow your doctor’s instructions for doing physical therapy. You may need to meet with your physical therapist soon after the injection to take advantage of the pain relief in your muscles.
  • You may have pain relief for weeks or even months. In some cases, though, you may need to have more than one trigger point injection. Talk to your doctor about how often you will need this treatment.

    Call Your Doctor

    After you arrive home, contact your doctor if any of the following occurs:

  • Signs of infection, including fever and chills
  • Redness, swelling, increasing pain, bleeding, or discharge from the injection site
  • Numbness, tingling, pain, or weakness
  • Any new or unexplained symptoms