Can Monosodium Glutamate (MSG) cause headaches?

MSG and Headaches: Evidence-Based Assessment

The evidence for MSG causing headaches in real-world conditions (when consumed with food) is weak and inconsistent, with the strongest systematic review finding no significant relationship between MSG ingestion with food and headache development. 1

Critical Evidence Analysis

Systematic Review Findings (Highest Quality Evidence)

The most rigorous systematic review examining MSG and headache separated studies based on whether MSG was consumed with or without food—a critical distinction given the dramatically different glutamate kinetics under these conditions 1:

• MSG consumed WITH food (5 papers, 6 studies): None showed significant differences in headache incidence except for one female subgroup in a single study 1
• MSG consumed WITHOUT food (5 papers, 7 studies): Four studies showed significant differences, but these studies had fatal methodological flaws 1

Methodological Problems in Positive Studies

The studies showing MSG-headache associations suffer from critical design flaws 1:

• MSG was administered in solution at concentrations >2%, making the distinctive taste readily identifiable 1
• Proper blinding was impossible at these concentrations, introducing substantial bias 1
• These artificial conditions (high-concentration liquid MSG on empty stomach) do not reflect real-world dietary exposure 1

Clinical Context

Real-World MSG Exposure

MSG in actual food products exists at much lower concentrations than experimental studies, and food matrices significantly alter glutamate absorption kinetics 1. The systematic review authors concluded that further studies are required to establish any causal relationship between MSG ingestion and headache 1.

Historical Perspective

While MSG has been historically labeled as a headache trigger 2, 3, and older observational reports suggested associations 2, these were not based on properly controlled studies. The 2016 narrative review noted that MSG dissolved in liquid has evidence for triggering headaches, but this does not translate to MSG consumed in food 3.

Susceptible Subgroups

Some individuals may experience symptoms (including headache) as part of "MSG symptom complex," but this appears to be uncommon and may represent hypersensitivity reactions rather than a universal effect 4. Case reports exist, but these represent rare occurrences rather than typical responses 4.

Clinical Recommendations

For patients reporting MSG-related headaches:

• Consider a time-limited elimination trial of MSG-containing foods if the patient has documented temporal associations between specific foods and headache onset 2, 3
• Be aware that MSG appears on labels as "natural flavor," "flavoring," or "hydrolyzed vegetable protein" (which contains 10-30% MSG) 2
• Recognize that attribution is challenging since headache is common in the general population and many factors can trigger headaches 3

For headache prevention priorities, focus on proven triggers:

• Caffeine withdrawal has the strongest evidence for triggering headaches 3
• Limit acute headache medications to <2 days per week to prevent medication-overuse headache 5
• Avoid medications containing barbiturates, caffeine, butalbital, or opioids, which carry the highest rebound risk 5

Important Caveats

The lack of strong evidence does not definitively prove MSG never causes headaches—it means current research methodology has failed to demonstrate a consistent, reproducible relationship under realistic dietary conditions 1. Individual responses vary significantly, and some patients may genuinely experience MSG-triggered headaches despite weak population-level evidence 3.