A metallic taste in the mouth occurs as a side effect of various medications or due to a nerve disorder called dysgeusia, according to Dr. Melissa Conrad Stöppler of Medicine Net. An impaired sense of smell, smoking, poor dental hygiene and oral infections also produce a metallic taste, states Natalie Kilgore on HowStuffWorks.
Certain medications, such as antibiotics and antihistamines, alter a person’s sense of taste, says Stoppler. Most of these are temporary cases that resolve once the medication is discontinued. Another common cause is dysgeusia, a disorder of the nerves that control sensations of taste.
Dysgeusia often leaves a persistent metallic taste in the mouth due to hormonal changes during pregnancy, particularly in the first trimester, Kilgore reports. The unusual taste typically disappears once the hormones stabilize in the second trimester. Moreover, an impaired sense of smell causes a metallic taste, as smell and flavor are closely linked and the tongue’s nerve endings have the ability to sense irritation within the nasal area. A nasal infection, cold, runny nose or sinusitis can cause a metallic sensation.
Unhealthy practices, such as smoking and poor dental hygiene, also lead to a foul taste, says Kilgore. Additionally, oral infections such as periodontitis and gingivitis make the gums bleed, releasing iron that breaks down in the mouth and leaves a strong metal taste.