Palo Azul—Spanish for “blue stick”—is a herbal tea made from the bark of the Eysenhardtia polystachya tree, native to Mexico and parts of Central America. Its most famous feature is the striking blue tint the tea can take on under sunlight, a quality that has fascinated herbalists for centuries. Traditionally, it’s been used in folk medicine for kidney and urinary health, detoxification, and general well-being.

A Brief History & Uses

For generations, indigenous communities have brewed Palo Azul as a natural remedy to:

• Support kidney function and urinary tract health
• Help flush toxins from the body
• Aid hydration and overall detox
• Reduce mild inflammation

While modern science is still studying Palo Azul’s active compounds, it remains popular among natural health enthusiasts for its gentle, caffeine-free properties and unique, almost mystical appearance.

Ingredients You’ll Need

• 1 ounce (28 g) of Palo Azul bark (available from herbal shops or online)
• 1 gallon (3.8 L) of water
• Optional: lemon or cinnamon for added flavor

How to Make Palo Azul Tea

Step 1: Rinse the Bark
Quickly rinse the Palo Azul bark under cool running water to remove any dust or debris.

Step 2: Boil the Water
In a large pot, bring 1 gallon of water to a boil.

Step 3: Add the Bark
Once the water reaches a rolling boil, add the 1 ounce of bark.

Step 4: Simmer Gently
Lower the heat and let it simmer for 1–2 hours. The longer you simmer, the richer the flavor and the deeper the color.

Step 5: Strain & Serve
Remove the bark pieces using a strainer. Serve hot for a warming herbal drink, or refrigerate and enjoy it cold.

Tips for Best Results

• For a more concentrated brew, use less water or simmer for longer.
• To see the famous blue tint, pour the tea into a glass and hold it to sunlight or bright light.
• Palo Azul can be re-brewed: simply add more water to the same bark and simmer again—though the flavor will be lighter.

Storage

Store your tea in a sealed glass container in the refrigerator for up to 5 days. Reheat gently or serve chilled.

A Note on Safety

Palo Azul is generally considered safe in moderate amounts, but if you have a medical condition or are pregnant/nursing, consult your healthcare provider before adding it to your routine.

What’s in Palo Azul? (The phytochemicals)

Palo Azul (Eysenhardtia polystachya) is especially rich in polyphenols, notably flavonoids (flavones, flavanones, isoflavones), chalcones/dihydrochalcones, and other phenolic compounds. Multiple lab studies and reviews have isolated and cataloged these constituents from the bark/heartwood—the very material used to brew the tea. cite

Recent work keeps expanding that list. For example, a 2025 pharmacology paper identified compounds such as Coatline B and Matlaline, and explored their antioxidant properties and roles in nitric oxide and hydrogen sulfide signaling relevant to renal inflammation. cite

Analytical surveys (including capillary electrophoresis and other profiles) further support that Palo Azul contains an array of phenolics that likely underlie its traditional use for kidney/urinary wellness.

Key groups found in Palo Azul extracts

• Flavonoids (flavones, flavanones, isoflavones) and related phenolics. cite
• Chalcones and dihydrochalcones (often implicated in the tea’s characteristic fluorescence/blue tint in light due to their optical properties). cite
• Additional secondary metabolites reported across the genus Eysenhardtia in broader phytochemical reviews. cite

What does research say Palo Azul might do?

Quick reality check: most data are in vitro or animal studies. Promising doesn’t mean proven in humans yet.

• Antioxidant & anti-inflammatory activity: Flavonoid-rich extracts from E. polystachya show significant antioxidant capacity and anti-inflammatory effects in preclinical models. cite
• Kidney/urinary support (nephroprotection & diuresis): Traditional “kidney wood” use aligns with experimental work exploring renal protection and diuretic effects; the 2025 study on Coatline B/Matlaline investigated mechanisms tied to inflammation pathways in acute kidney injury models.
• Broader pharmacology: Reviews summarize activity across oxidative stress, glycation, microbial growth, and more for Eysenhardtia constituents—again, mostly preclinical. cite

How to make Palo Azul tea (recap)

You’ll need

• 1 ounce (28 g) Palo Azul bark
• 1 gallon (3.8 L) water
• Optional: lemon, cinnamon

Steps

1. Rinse the bark.
2. Bring water to a boil; add bark.
3. Simmer 1–2 hours (longer = deeper color/flavor).
4. Strain and serve hot, or chill.
   Tip: pour into a clear glass and hold to sunlight—you may see the famous blue fluorescence (thanks to those polyphenols). cite

Safety & smart use

Palo Azul is caffeine-free and generally well-tolerated in customary amounts, but comprehensive human trials are limited. If you’re pregnant, nursing, have kidney conditions, or take medications, check with your clinician. Popular press roundups echo the “promising but preliminary” state of evidence. cite

Sources & further reading

• Pérez-Gutiérrez RM. Properties of flavonoids isolated from the bark of E. polystachya (open-access review). cite
• García-Campoy A. Eysenhardtia genus: phytochemical & pharmacological review (2020). cite
• Pablo-Pérez SS et al. Ethanolic extract study—antioxidant/anti-inflammatory context (2018). cite
• Parra-Espejel EJ et al. Nephroprotective investigation; Coatline B & Matlaline (2025).
• UTEP Herbal Safety “Kidneywood” fact sheet (analytical references, background). cite