According to the National Institute of Health, a migraine is a headache characterized by intense pulsing and throbbing in the affected area of the head. They generally occur in succession, with on average five occurrences in a seventy-two-hour period. These migraines can be so severe that they may initiate other symptoms, like nausea and light sensitivity. Prior to the migraine setting in, people usually see flashing lights or visual changes. They can be caused by anxiety or hormonal changes.
Odors that cause migraines include:

1. Cigarette smoke
According to the American Headache Society, cigarette smoke odors have brought on migraines. There are a couple ways that cigarette smoke can trigger migraines. The use of nicotine itself causes dilation of the blood vessels, which decreases blood flow to the brain and in turn can cause migraine. Additionally, those who inhale second hand smoke can experience these effects. Some people are allergic to second hand cigarette smoke and this can initiate migraines.

2. Food odors
The scent of cheese, salami, and fermented foods can trigger migraines for certain individuals. These foods are all characterized by pungent smells that may contribute to the onset of migraines. Also, the strong scent of chocolate may bring on migraines. It can also be noted that actually eating these foods mentioned above is also linked with bringing about migraines.

3. Perfumes
The scent of perfumes can bring on migraines. There are many reasons for this. One of the reasons is that some perfumes contain synthetic ingredients, which are known to cause allergies. These allergies can then bring on migraines as a symptom. These chemical compositions are more likely than natural compositions to bring about migraine headaches. According to Healthline, perfume is a common trigger for migraine symptoms.

4. Cleaning chemicals
Cleaning chemicals are some of the most likely to cause migraines. As in the case of perfumes and air fresheners, this is because they often contain unnatural components in their ingredients list. Some of the most common cleaning chemicals that can bring on migraines are bleach, Windex, and carpet cleaners. Solvents and detergents are two types of cleaning ingredients that can irritate migraine-sufferers.

5. Scented candles
Scented candles are some of the most likely culprits in causing migraines. This is because these products can contain fragrances that are made up of unnatural chemical components. In order to produce a product that can scent an entire room, candle manufacturers often have to use synthetic fragrances made in a lab.

6. Air fresheners
This is one of the most common smells that trigger migraines. Sixteen percent of those surveyed have attributed air fresheners as a cause for migraines. Because of this, many companies have an all natural or organic line that is less likely to trigger migraines.