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Q: What can cause someone to have a constant sense of smelling metal or heavy cigarette smoke? Could it be caused by a vitamin deficiency or PMS?

A: Having an altered sense of smell is actually quite common. A survey of adult Americans found that two-thirds had experienced a problem with smell some time during their lives.

Smell disorders are often classified as one of the following:

  • Complete loss of the ability to detect odors, called anosmia
  • Decreased sense of smell with some ability to detect odors, called hyposmia
  • Distorted sense of smell, called dysosmia

Your symptoms suggest that you have dysosmia. It could be that your brain is registering an odor when none is present in the environment. Another possibility is that you have become more sensitive to an odor that doesn’t bother other people. When this occurs, the odor is usually described as an unpleasant one.

As to what might be causing your dysosmia, there are a number of possibilities. While vitamin or mineral deficiencies can cause altered smell, this would be very unlikely unless you are on a very restricted diet or have an intestinal problem that impairs absorption of nutrients. Regarding an association of premenstrual syndrome (PMS) with altered smell, I was not able to find any studies to suggest that the two are related.

Here are some other causes of altered smell:

  • Some medications; In general, medications cause a metallic taste rather than a metallic smell.  The antibiotic metronidazole (Flagyl) is probably the most common cause of a metallic taste in the mouth and potentially a metal smell.
  • Exposure to certain chemicals
  • Pregnancy
  • A cold or sinus infection
  • Bad breath
  • A history of head trauma
  • Side effect of anesthesia
  • Migraine

People with depression, anxiety, or other psychologic disturbances can have an altered sense of smell.

If the dysosmia persists, call your doctor. He or she will likely arrange an appointment or perhaps refer you to an ear, nose, and throat specialist.