How to Make Aspirin From Willow

Easy Steps to Extract Aspirin From Willow

Willow bark (Salix sp.) has a characteristic appearance.
Willow bark (Salix sp.) has a characteristic appearance. Michael Hieber, Getty Images

Willow bark contains a chemical active ingredient called salicin, which the body converts into salicylic acid (C7H6O3) — a pain reliever and anti-inflammatory agent that is the precursor to aspirin. In the 1920s, chemists learned how to extract salicylic acid from willow bark to reduce pain and fever. Later, the chemical was modified into the present form of aspirin, which is acetylsalicylic acid. While you can prepare acetylsalicylic acid, it's also nice to know how to get the plant-derived chemical directly from willow bark. The process is extremely simple:

Finding Willow Bark

The first step is to correctly identify the tree that produces the compound. Any of a number of species of willow contain salicin. While nearly all species of willow (Salix) contain salicin, some do not contain enough of the compound to use for a medicinal preparation. White willow (Salix alba) and black or pussy willow (Salix nigra) are most often used to obtain the aspirin precursor. Other species, such as crack willow (Salix fragilis), purple willow (Salix purpurea), and weeping willow (Salix babylonica), also may be used. Since some trees are toxic or else do not contain the active compound, it's important to correctly identify willow. The bark of the tree has a distinctive appearance. Trees that are one or two years old are most effective. Harvesting bark in the spring results in higher potency than extracting the compound in other growing seasons. One study found salicin levels varied from 0.08% in fall to 12.6% in spring.

How to Get Salicin From Willow Bark

  1. Cut through both the inner and outer bark of the tree. Most people advise cutting a square into the trunk. Don't cut a ring around the trunk of the tree, as this can damage or kill the plant. Don't take bark from the same tree more than once a year.
  2. Pry the bark from the tree.
  3. Shred the pink section of the bark and wrap it in a coffee filter. The filter will help keep dirt and debris from getting into your preparation.
  4. Boil 1-2 teaspoons of fresh or dried bark per 8 ounces of water for 10-15 minutes.
  5. Remove the mixture from heat and allow it to steep for 30 minutes. A typical maximum dose is 3-4 cups per day.

Willow bark may also be made into a tincture (1:5 ratio in 30% alcohol) and is available in powdered form containing a standardized quantity of salicin.

Comparison To Aspirin

Salicin in willow bark is related to acetylsalicylic acid (aspirin), but it is not chemically identical. Also, there are additional biologically active molecules in willow bark which may have therapeutic effects. Willow contains polyphenols or flavonoids that have anti-inflammatory effects. Willow also contains tannins. Willow acts more slowly as a pain-reliever than aspirin, but its effects last longer.

Since it is a salicylate, salicin in willow bark should be avoided by persons with a sensitivity to other salicylates and may carry a similar risk of causing Reye syndrome as aspirin. Willow may not be safe for persons with clotting disorders, kidney disease, or ulcers. It interacts with several medications and should only be used as approved by a healthcare provider.

Uses of Willow Bark

Willow is used to relieve:

  • headache pain
  • muscle cramps
  • menstrual pain
  • osteoarthritis symptoms
  • fever
  • back pain


WedMD, "Willow Bark" (retrieved 07/12/2015)
University of Maryland Medical Center, "Willow Bark" (retrieved 07/12/2015)

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Helmenstine, Anne Marie, Ph.D. "How to Make Aspirin From Willow." ThoughtCo, Aug. 25, 2020, Helmenstine, Anne Marie, Ph.D. (2020, August 25). How to Make Aspirin From Willow. Retrieved from Helmenstine, Anne Marie, Ph.D. "How to Make Aspirin From Willow." ThoughtCo. (accessed April 22, 2021).