Smell Sensitivity and Migraines

Odors play a role in triggering migraines, and osmophobia (increased sensitivity to and intolerance to smells) is a common part of the migraine experience. Generally, chemical fumes such as cleaners and gasoline are those most likely to induce a migraine attack. During a migraine, many odors can be bothersome.

It isn't quite clear why some people are more sensitive to noxious smells. But if you are predisposed to migraines, you are more likely to experience migraines and non-migrainous headaches when you are exposed to strong smells. Headaches triggered by odors tend to be severe and are often accompanied by nausea.

There are a variety of odors known to precipitate migraines. The most common include:

• Car exhaust
• Pesticides
• Perfume
• Nail polish
• Cigarette smoke
• Cleaning products

If you have recurrent migraines, exposure any of these scents can be enough to cause an episode.

Other examples of odors that may trigger a migraine include:

• Asphalt
• Carpeting
• Paint or paint thinners
• Detergents
• Leather
• Combustible gas 

Odors are more likely to induce a migraine if you are exposed for a prolonged period of time (more than 15 minutes) and if you are in an enclosed space.

Awareness and avoidance of your migraine triggers are key to improving your quality of life. There are several steps you can take to thwart olfactory-induced migraines:

Be observant. Do you tend to have migraines when you are in certain locations? You could be extra sensitive to the fumes in these settings.

At least 50 percent of people who have recurrent migraines experience premonitory symptoms, which occur during the first (prodromal) stage of a migraine. If you notice symptoms such as moodiness, dizziness, or fatigue before your migraines, you can try to avoid the fumes that bother you during this time.

When you are exposed to fumes that could trigger a migraine, leave the environment, open a window, or step outside if you can.

For example, if you discover that perfume is one of your migraine triggers, consider discussing a perfume-free space with your boss or roommate. Some people experience a condition known as sick building syndrome, which is characterized by a variety of symptoms related to chemicals in an enclosed environment. Good circulation and avoidance of too many noxious substances can help prevent your migraines and can keep your workplace healthier for everyone.

If you work closely with paint thinner, gasoline, or another odorous substance that you are sensitive to, consider switching to another work setting where you can avoid these exposures.

During a migraine, you may notice an amplified sense of smell or a sense that certain odors are unpleasant. This phenomenon is called osmophobia, and the vast majority of migraineurs experience it at some time or another.

Osmophobia can be particularly unpleasant during a migraine. You may be disgusted by the smell of raw food, repulsed by the smell of food that is cooking, and repelled by food that doesn't bother you at other times. You might feel that many foods are rotten, or you may detect the persistent smell of food on your hands or in your surroundings.

Other scents, such as polishes and chemical cleaners, can seem to produce exceedingly strong odors when you are having a migraine, though they may seem benign at other times.

Osmophobia classically occurs during a migraine attack, just like photophobia (sensitivity to light) and phonophobia (sensitivity to sound). But, if you have recurrent migraines, you may have an amplified sense of smell (without aversion to scents) between migraine attacks as well.

Interestingly, this hypersensitivity and aversion to smells could be related to a diminished size of the olfactory bulb (the receptor in the brain that processes input of odors). Small studies have suggested that people with migraines seem to have a smaller olfactory bulb than people without migraines and that people who have both migraines and osmophobia have an even smaller olfactory bulb volume.

It may seem strange that a smaller structure would be more sensitive, but this often happens (such as with the pain and discomfort that is common with nerve dysfunction of neuropathy).

Some researchers suggest that diminished blood flow to the olfactory bulb could be the cause of atrophy (shrinking) and dysfunction of this structure. However, these structural changes are subtle, and measuring your olfactory bulb is not a standard procedure.

Migraineurs experience other odor-related symptoms too, but with a much lower frequency than osmophobia. Two examples are phantosmia (smelling an odor that is not there, a "phantom smell") and cacosmia (perceiving a mild or pleasant smell as noxious).

Living with migraines requires adapting your mindset and making adjustments when you need to. Sometimes, putting up with certain things— such as odors— can cause you to suffer for days from a migraine that could have been avoidable. Don't hesitate to take care of yourself by avoiding your migraine triggers, including the fumes that cause you to have a migraine, whenever possible.