Complications of Local Anesthesia

Local Anesthesia is useful in many dental treatment procedures and there are many complications associated with the administration technique and also with the composition of certain components of the agent present like allergic reactions and other conditions which are divided into Local and Systemic. One of the most common Complication seen in Syncope which can be caused due to many reasons and the Dentist should be ready at all times to deal with it in a rapid manner.

Some localized complications due to Local anesthesia are – Anaesthetic Necrosis which is is seen as a localized necrosis of soft tissue surrounding the injection site. The complications can be as simple as the above mentioned necrosis or some times severe systemic complications like Cardiac Arrest which can be seen if proper history of the patient is not collected before going ahead with the administration of LA Agent.

Complications due to Local Anesthesia:


Any deviation from the normally expected pattern during or after the securing of regional analgesia is termed as a complication due to Local Anesthesia.

In this image a case of Occulomotor palsy which is seen as a complication of inferior alveolar nerve block when it is given into the parotid gland and affects the Facial nerve.

Complications / Adverse Effects of Local Anesthesia are classified into 3 types:

1) Primary or Secondary:

A Primary complication is one that is caused and manifested at the time of anesthesia. A Secondary complication is one that is manifested later, even though it may be caused at the time of insertion of the needle and injection of the solution.

2) Mild or Severe:

A mild complications is one that exhibits a slight change from the normally expected pattern and reverses itself without any specific treatment. A Severe complication manifests itself by a pronounced deviation from the normally expected pattern and requires a definite plan of treatment.

3) Transient or Permanent:

A Transient complication is one that, although severe at the time of occurrence, leaves no residual effect. A Permanent complication would, of course, leave a residual effect, even though mild in nature.

Complications / Adverse Effects may be further divided into 2 groups:

1. Those attributed to the solutions used:

This group includes those complications that result from the absorption of the anesthetic solution:

  • Toxicity
  • Idiosyncrasy
  • Allergy
  • Anaphylactoid reactions
  • Infections caused by contaminated solutions
  • Local irritations or tissue reactions caused by the solution

2. Those attributed to the insertion of the needle:

This group includes those complications attributed to the insertion of the needle:

  • Syncope (fainting)
  • Muscle Trismus
  • Pain or Hyperalgesia
  • Edema
  • Infectious
  • Broken Needles
  • Prolonged anesthesia other than from the anesthetic solution
  • Hematoma
  • Sloughing
  • Neurological complications

Complications can also be divided based on Local and Systemic Effects:

1. Local Complications:

  • Needle Breakage
  • Pain on injection
  • Burning on injection
  • Persistent anesthesia (Paresthesia)
  • Trismus
  • Hematoma
  • Infection
  • Edema
  • Slugging of tissue
  • Soft tissue injury (lip, cheek, tongue, palate)
  • Facial Nerve Paralysis
  • Postoperative intraoral lesions – Recurrent Aphthous Stomatitis, Herpes Simplex
  • Visual Disturbance
  • Intravascular injection
  • Failure to obtain anesthesia

2. Systemic Complications:

  • Toxicity due to overdose
  • Allergy
  • Idiosyncrasy
  • Syncope
  • Drug interaction
  • Serum hepatitis
  • Occupational dermatitis
  • Respiratory arrest
  • Cardiac arrest
  • Hyperventilation
  1. October 12, 2013
  2. October 12, 2013
  3. June 7, 2016
  4. April 27, 2017
  5. October 27, 2017
  6. November 4, 2017
  7. November 5, 2017
  8. January 31, 2018
  9. June 25, 2018
  10. July 6, 2018
  11. October 12, 2018
  12. October 15, 2018

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