What Is an MSG-Induced Headache?

Monosodium glutamate (MSG) is the sodium salt of an amino acid found naturally in our bodies called glutamic acid. Found naturally in many foods, like cheese and tomatoes, MSG can also be produced through the fermentation of starch, sugar, or molasses, and added to foods. Most notably, MSG is used in Chinese cuisine as a flavor enhancer.

Some people have a sensitivity to MSG that results in a headache and other symptoms. First identified as "Chinese-restaurant syndrome" in 1968, further research suggests the culprit is MSG.

Scientists have been unable to link MSG to headaches and other symptoms conclusively. Regardless, many people commonly report MSG as a headache or migraine trigger, and researchers acknowledge that a small percentage of people may have a short-term reaction to the additive.

The mechanism behind MSG-induced headaches is not fully understood. MSG is an excitatory amino acid that binds to MNDA receptions in the brain. This activation leads to the release of nitric oxide, which then leads to the dilation or widening of blood vessels around the skull.

Most people with an MSG-related headache describe a tightening or even burning head sensation. People will also commonly notice muscle tenderness around their skull.

In people with a history of migraines, MSG triggers a migraine—in this instance, people usually report a classic throbbing or pulsating headache.

An MSG-induced headache typically develops within 1 hour of consuming MSG and resolves within 72 hours of MSG consumption. Also, an MSG-induced headache has at least one of the following five characteristics:

• Bilateral (i.e., both sides of the head)
• Mild to moderate intensity
• Pulsating quality (i.e., throbbing)—like a migraine
• Associated with other symptoms that include: facial flushing, chest and face pressure, burning feeling in the neck, shoulder, and/or chest, dizziness, and stomach discomfort.
• aggravated by physical activity

A study published in the journal Cephalalgia also found that people who consumed a high amount of MSG—such as a sugar-free soda containing 150mg/kg of MSG—had an increase in their blood pressure, although this was temporary. Chronic daily intake of high doses of MSG may also cause fatigue.

For people who are sensitive to MSG, the only treatment is to avoid foods containing MSG. Foods that commonly contain added MSG are Chinese food (in particular, soy sauce), canned vegetables, soups, and processed meats.

Though generally regarded as safe by the U.S. Food & Drug Administration, added MSG must be listed in the ingredients list on food packaging. Look for these terms:

• Monosodium glutamate or MSG
• hydrolyzed fat
• hydrolyzed protein
• all-natural preservatives 

MSG-induced symptoms are typically not severe and subside on their own entirely within 72 hours. However, if your symptoms do not appear to resolve or continue worsening after 48 hours, speak to your doctor, as it may be something more serious.

To help symptoms subside faster, drink only water, and a lot of it—at least half of your body weight in ounces. For example, if you weigh 150 pounds, drink at least 75 ounces of water. Adequate hydration will help your kidneys to process MSG and flush it from your system.

In addition, limit sodium intake until symptoms dissipate. Sodium promotes water retention and will make it harder for your body to release the MSG through urination.

If you suspect MSG is a headache or migraine trigger for you, avoiding it is probably your best bet. Unlike other food sensitivities, it is unlikely that you can build up a tolerance for MSG. The best way to avoid MSG is to read food labels and inquire at restaurants if MSG has been added to any foods.

Keeping a diary of your headache symptoms and possible triggers can help you and your doctor to pinpoint the causes of your headaches and develop the right treatment plan for you.