Does Ouzo Crystallize in Your Stomach? Myth vs. Chemistry

No. Ouzo does not crystallize in the stomach. This is a myth.

What Is Ouzo?

Ouzo is a Greek anise-flavored spirit (~37.5–50% ABV). Its characteristic cloudiness when diluted with water (the "ouzo effect") is due to spontaneous emulsification of anethole (the essential oil of anise), not crystallization.

The Science

• Anethole is soluble in ethanol but poorly soluble in water.
• When water is added, ethanol concentration drops → anethole precipitates as nanoscale droplets (microemulsion), scattering light → milky appearance.
• This is a liquid-liquid phase separation, not solid crystallization. The droplets remain liquid at body temperature.
• In the stomach (37°C, aqueous, acidic), the emulsion persists or further disperses; no solid crystals form.

Other Components

Ethanol, water, fennel, coriander, star anise, mastika — all liquids or volatile oils at body temperature. None crystallize under gastric conditions.

Actual Effects of Ouzo

• Alcohol absorption → intoxication, gastric acid stimulation
• Anethole: mild antispasmodic, carminative (traditional digestif claim)
• Excess: gastritis, reflux, dehydration, impaired judgment

Enjoy ouzo responsibly (diluted, with meze, good company). The "crystallization" story is a colorful tavern tale, not biochemistry.