Prickly Ash belongs to the Zanthoxylum genus, a group of deciduous shrubs and small trees in the citrus family, Rutaceae. This plant is known for producing a tingling or numbing sensation when chewed, leading to its common name, “toothache tree.” The bark and berries of certain Zanthoxylum species have been integral to traditional North American healing systems for their stimulating and pain-relieving effects.
Botanical Identity and Habitat
Prickly Ash includes two primary species used in North American herbalism: Zanthoxylum americanum (Northern Prickly Ash) and Zanthoxylum clava-herculis (Southern Prickly Ash or Hercules’ Club). Both species are thorny, featuring sharp spines or prickles on the twigs and sometimes on the trunk. As deciduous plants, they possess pinnately compound leaves that often emit a lemon-like fragrance when crushed, reflecting their relation to citrus.
Zanthoxylum americanum is the more widespread species, ranging from Quebec and Ontario south to Virginia and west to Oklahoma. It prefers moist to dry deciduous woods and often forms thickets. In contrast, Zanthoxylum clava-herculis is native to the southeastern United States, ranging from coastal Virginia down to Florida and west to Texas. This Southern species is frequently found in maritime forests and along the coast.
Traditional and Modern Uses
Native American tribes first recognized the medicinal attributes of Prickly Ash. They traditionally used the bark and roots to relieve the pain of toothaches by chewing the plant material or applying a crushed paste directly to the gums, which gave rise to the nickname “toothache tree.” It was also applied to treat joint discomfort, rheumatism, and sore muscles.
Today, Prickly Ash is valued primarily as a circulatory stimulant, improving peripheral blood flow. This is beneficial for conditions like Raynaud’s syndrome, varicose veins, and intermittent claudication. The stimulating effect helps bring fresh, oxygenated blood to stagnant areas, aiding in the removal of metabolic waste. It is also recognized as a sialagogue, promoting salivation and digestive enzyme production, which supports overall digestive health.
The plant is used in several preparations, including teas or decoctions made from the bark, and liquid extracts known as tinctures. For localized pain, such as muscle soreness or joint inflammation, the bark or powdered preparations can be applied topically as a poultice or liniment. The berries share many of the same properties as the bark and are sometimes used as a spice, similar to the related Sichuan pepper.
Key Active Compounds
The biological actions of Prickly Ash stem from a diverse array of phytochemicals, primarily alkaloids, lignans, and coumarins. The distinct tingling and numbing sensation is attributed to alkylamides, such as herculin, which have a localized anesthetic effect. These compounds are believed to be more prevalent in Z. clava-herculis.
The plant contains various classes of alkaloids, including isoquinoline alkaloids like chelerythrine and nitidine, and furoquinoline alkaloids such as fagarine. Chelerythrine has demonstrated anti-inflammatory and antimicrobial properties. Lignans, such as sesamin and asarinin, are also present and are known for their antioxidant and anti-inflammatory effects.
Northern Prickly Ash (Z. americanum) is characterized by pyranocoumarins, including dipetaline and xanthoxyletin, which contribute to its circulatory stimulating action. These compounds work together to produce the herb’s effects, from improved blood flow to its analgesic properties, providing a scientific basis for its traditional applications.
Safety and Preparation Guidelines
Prickly Ash is generally safe when used within recommended guidelines, but precautions are necessary due to its potent actions. Individuals taking anticoagulant medications, such as warfarin, should exercise caution, as the herb may enhance the blood-thinning effect, increasing the risk of bleeding. Caution is also advised for those with acute inflammatory conditions of the stomach, as the stimulating nature of the herb may exacerbate irritation.
Pregnant or breastfeeding women are advised to avoid using Prickly Ash due to the lack of sufficient safety data and the potential for certain alkaloids to affect uterine tissue. While major side effects are uncommon, some individuals may experience mild digestive upset. Anyone considering its use should consult a healthcare provider, especially if they have pre-existing medical conditions or are on prescription medications.
The bark and berries are the medicinal parts most commonly used. A traditional preparation involves making a decoction by simmering 1–2 teaspoons of the dried bark in water for 10 to 15 minutes. Alternatively, a liquid extract (tincture) is often taken in small doses, typically a half to three-quarters of a teaspoon, three times daily. Dosage recommendations vary, so following the product’s instructions or consulting an experienced herbalist is important.