Metallic taste

Common causes include:

• gingivitis and/or periodontitis - in these cases pus is slowly seeping out from the gums giving rise to a sometimes metallic or bitter taste. Patients may also complain (or exhibit) halitosis.
• drugs which may cause a metallic taste include:
  • metronidazole
  • gold (1)
• idiopathic

Also consider (2):

• respiratory infections of the upper respiratory tract - especially of the tonsils and sinuses - can leave an unpleasant taste in the mouth
• gastric reflux - this may cause bitterness within the mouth
• oral dryness e.g. in Sjogren's syndrome - may lead to bitter taste or generalised loss of taste

If there is no oral cause such as gingival inflammation or systemic cause (e.g. drug therapy) to explain the patient's symptom then review the patient's social history to determine if there are any lifestyle stresses. In more than one third of patients with idiopathic taste disturbance there may be some psychological upset including anxiety and depression...such patients may also complain of a burning sensation affecting different surfaces of the mouth - mostly the tongue or lip - or complain of long-standing oral dryness (in the absence of clinical signs) ..the problem may last up to 2 years, there is data suggesting 77% of patients will have spontaneous remission of symptoms and further 15% spontaneous remission following psychological approaches (2).

Reference:

1. Answer back section - Professor Stephen Porter, Professor of Oral Medicine, University of London. Pulse (1999), 59 (11), 96.
2. Pulse (2004), 63 (47), 80.