From the Guidelines
Local anesthetic injections can indeed cause a metallic taste in the mouth, as evidenced by the potential signs and symptoms of local anesthetic systemic toxicity (LAST) which include metallic taste, among other neurological and cardiovascular effects. This is supported by the guidelines for the use of local anesthesia in office-based dermatologic surgery, which notes that patients may experience a metallic taste as an initial symptom of LAST, often accompanied by other symptoms such as circumoral numbness, facial tingling, and auditory changes 1. The occurrence of a metallic taste is thought to be related to the stimulation of taste receptors on the tongue by the anesthetic solution, particularly if it enters the bloodstream.
According to the study published in the Journal of the American Academy of Dermatology in 2016 1, the dose of local anesthesia needed for most dermatologic procedures is well below the manufacturer-recommended maximum, and anesthetic toxicity in the dermatologic setting is extremely rare. However, clinicians should still be mindful of the potential for toxicity and take steps to ensure patient safety, such as using ultrasonographic guidance and intravascular markers to avoid introducing the drug directly into a vessel.
Key points to consider include:
- The metallic taste is a potential symptom of LAST, which can also include seizures, central nervous system depression, and cardiac failure or arrest in severe cases 1.
- The effect is more likely to occur with higher doses or accidental intravascular injection.
- Patients may also experience numbness of the tongue or other oral tissues, which can alter taste perception.
- If a metallic taste occurs after receiving a local anesthetic, it's generally not cause for concern unless accompanied by other symptoms like dizziness, rapid heartbeat, or difficulty breathing, which could indicate a more serious reaction requiring immediate medical attention.
From the Research
Local Anesthetic Injections and Metallic Taste
- The available studies do not provide direct evidence that local anesthetic injections cause a metallic taste in the mouth 2, 3, 4, 5.
- However, a study on botulinum toxin A, which is also a type of injection, reported a case of metallic taste as an unusual reaction to the treatment 6.
- The pathogenesis of metallic taste remains unclear, but alteration in zinc metabolism has been suggested as a possible mechanism 6.
- Local anesthetic injections can cause various adverse effects, including ocular and neurological effects, allergies, and tissue necrosis, but metallic taste is not commonly reported 2, 3, 4, 5.
- Further research is needed to determine the relationship between local anesthetic injections and metallic taste, as the current evidence is limited and indirect 4.