Ruta graveolens, commonly known as rue, is a bitter-smelling evergreen herb used for centuries in traditional medicine to treat digestive complaints, menstrual irregularities, muscle spasms, and eye strain. It remains popular today in homeopathic remedies and herbal preparations, though its potent chemistry also makes it one of the riskier herbs to use without caution. Here’s what rue is actually used for, what science says about how it works, and what you need to know about its safety.
A Long History in Folk Medicine
Rue has been a staple of traditional healing systems across Europe, the Middle East, and Latin America for hundreds of years. Herbalists historically prescribed it as a digestive aid, a remedy for menstrual cramps, and a treatment for joint and muscle pain. In traditional New Mexican communities in the Southwestern United States, rue tea has been used for generations as a home remedy for a variety of ailments, including as an abortifacient to end early pregnancies.
The plant was also valued as an insect repellent and was believed to ward off plague during the Middle Ages. In culinary traditions, particularly in Ethiopian and some Mediterranean cuisines, small amounts of rue have been used as a bitter flavoring. The FDA lists rue oil as an approved flavoring agent, though the amounts used in food are extremely small compared to medicinal doses.
What’s Inside the Plant
Rue’s biological activity comes from a remarkably complex chemical profile. Researchers have identified 231 distinct compounds in the plant, spanning several major categories: alkaloids, coumarins (including furanocoumarins like bergapten), flavonoids, volatile oils, steroids, and anthraquinones. Alkaloids are the most abundant group, particularly acridone and quinoline types, followed closely by coumarins and related compounds.
These aren’t just botanical curiosities. Many of these compounds interact with the body in measurable ways. The coumarins and flavonoids are largely responsible for the plant’s anti-inflammatory and muscle-relaxing properties, while the furanocoumarins (especially bergapten) are the source of rue’s well-known ability to cause skin reactions in sunlight. The alkaloids, meanwhile, have shown enough biological activity that researchers are studying them as potential templates for new herbicides.
How Rue Relaxes Muscles and Reduces Spasms
One of rue’s best-supported traditional uses is as an antispasmodic, meaning it helps relax involuntary muscle contractions. Laboratory research on rat airway tissue found that a rue extract acted as a non-competitive antagonist, gradually reducing the maximum contraction that muscle tissue could achieve. In practical terms, the extract didn’t just block a single signal telling the muscle to tighten. It appeared to interfere with the underlying ion channels that allow muscles to contract in the first place.
Several compounds in the plant likely contribute to this effect. Coumarins and benzofurans found in plants of the Rutaceae family (rue’s botanical family) can block potassium currents in muscle cells. Rutin, a flavonoid present in rue, has shown dose-dependent relaxant effects on intestinal smooth muscle in animal studies. This combination of muscle-relaxing compounds helps explain why rue tea has traditionally been used for stomach cramps, intestinal spasms, and menstrual pain.
Homeopathic Uses for Eye Strain
In homeopathy, ruta graveolens is one of the most commonly recommended remedies for eye strain. Homeopathic pellets made from rue flowering tops are marketed specifically for fatigue, burning, and tired eyes caused by prolonged use of digital devices, reading in poor light, or other visually demanding tasks. These products, typically sold in highly diluted preparations like 6C potency, are available over the counter in pharmacies.
Homeopathic practitioners also recommend ruta for tendon and ligament injuries, repetitive strain conditions, and bruised bones. It’s worth noting that homeopathic dilutions contain little to no detectable plant material, so the safety concerns associated with rue as an herb don’t apply to these preparations in the same way. However, the evidence for homeopathic efficacy in general remains a subject of debate in mainstream medicine.
Serious Safety Risks
Rue is not a gentle herb. Its most well-known danger is phototoxicity: the furanocoumarins in the plant (psoralens) react with ultraviolet light to cause painful skin reactions. Published case reports describe a family, including a 5-year-old and 6-year-old, who developed redness, blistering, and lasting dark patches on their skin simply from handling the fresh plant and then going into sunlight. If you grow rue in your garden, wearing gloves when touching it is essential.
Ingesting rue in large amounts poses far greater risks. Data from a South American poison center showed that people who consumed rue tea in high doses for self-managed abortions experienced liver damage, kidney problems, and blood abnormalities at elevated rates. In severe cases, large ingestions have caused multiorgan failure, dangerous drops in blood pressure, and electrolyte imbalances serious enough to require emergency dialysis. Traditional medicine texts have long cautioned that the line between a “therapeutic” dose of rue tea and a toxic one is uncomfortably thin.
Rue and Pregnancy
Rue has a long, cross-cultural history of use as an abortifacient. The exact mechanism hasn’t been fully established, but it likely involves either disrupting the uterine lining (similar to how progesterone-blocking drugs work) or stimulating uterine contractions (similar to prostaglandin-based medications). Regardless of the mechanism, the risk of serious toxicity from the doses needed to produce this effect makes self-use dangerous. The cases of organ damage and life-threatening poisoning in the medical literature almost always involve people using rue for this purpose.
Limited Clinical Evidence in Humans
Despite centuries of traditional use, very little high-quality human research exists on rue. One pilot study gave a homeopathic preparation of ruta graveolens to 31 patients with advanced cancer to assess whether it could improve quality of life or slow tumor progression. The study was open-label and uncontrolled, meaning there was no placebo group for comparison, which makes it impossible to draw firm conclusions from the results.
Most of what we know about rue’s biological effects comes from laboratory experiments on isolated tissues and animal models. These studies consistently show anti-inflammatory, antispasmodic, and antimicrobial activity, but lab results don’t automatically translate into safe or effective treatments for people. The gap between “this compound relaxes rat intestinal tissue in a dish” and “this herb is a reliable treatment for stomach cramps” is significant, and rue hasn’t crossed it with clinical data yet.
Practical Considerations
If you’re encountering rue as a garden plant, handle it with gloves and long sleeves, especially on sunny days. The phototoxic reaction can occur even from brief contact with the sap followed by sun exposure, and children are particularly vulnerable.
If you’re considering rue as an herbal supplement or tea, be aware that standardized dosing guidelines don’t exist, the margin between a folk-remedy dose and a harmful one is narrow, and the plant is categorically unsafe during pregnancy. Homeopathic preparations of ruta graveolens are a different matter entirely due to their extreme dilution, and these carry minimal risk of the toxicity associated with the whole herb. For antispasmodic or anti-inflammatory purposes, other herbs with stronger safety profiles and better clinical evidence are widely available.