Why does my breath smell like metal?

Smell and taste overlap more than most people realize. MedlinePlus notes that much of what we perceive as taste is actually smell, so a metallic breath smell and a metallic taste usually have the same causes. Blood contains iron, which is why even a small amount from your gums gives a coppery, metal-like smell and taste. That makes bleeding gums the first thing to check.

If the main problem is the taste rather than the smell, our page on metallic taste in the mouth goes deeper into medicines and medical causes.

1. Gum disease. The NHS lists gums that bleed when you brush, floss or eat hard food as the main sign, and notes gum disease can lead to bad breath and a bad taste.
2. Recent dental work, a lost tooth or a cut in the mouth. Short-lived and usually obvious.
3. Nosebleeds or blood in nasal mucus. Blood can drip down the back of the throat, especially overnight.
4. Medicines. Cleveland Clinic lists some antibiotics (clarithromycin, metronidazole, tetracycline), allopurinol, captopril, lithium, methazolamide and metformin, because the drug can come out in saliva.
5. Supplements. Multivitamins with chromium, copper or zinc, zinc lozenges, prenatal vitamins, and iron or calcium supplements.
6. Colds and sinus infections. These change taste and smell for a while and resolve with the infection.
7. Pregnancy. The NHS lists a metallic taste as an early sign of pregnancy.
8. Kidney or liver disease, undiagnosed diabetes or certain cancers. Cleveland Clinic calls these uncommon causes that typically come with other symptoms.
9. Metal or chemical exposure. Lead, mercury and some insecticides can cause a metallic taste, and Cleveland Clinic advises seeing a doctor immediately if you suspect this.

For two weeks, brush twice a day with a soft brush angled at the gum line, clean between your teeth once a day even if the gums bleed at first, and clean your tongue daily. Gum bleeding from plaque often settles once the plaque is removed regularly, and the metallic smell goes with it. Drink water through the day, because a dry mouth makes any smell stronger.

If a medicine or supplement is the likely trigger, do not stop a prescribed medicine on your own. Ask the prescriber or a pharmacist whether timing, dose or an alternative could help. With supplements, check you are not taking more than the label dose or doubling up across products.

Blood that you cough up or vomit is not a mouth problem and needs medical attention. The NHS advises an urgent appointment for small streaks of blood in phlegm and emergency care for more than a few streaks, or blood with breathlessness or chest pain. Vomited blood, including vomit that looks like coffee grounds, also needs urgent care. A metallic smell together with an ammonia or urine smell is covered on our ammonia breath page.