Anas barbariae is the Latin name for the Muscovy duck, and in practice, the term almost always refers to a homeopathic preparation made from the heart and liver of that duck. You’ll find it listed on the label of Oscillococcinum, a widely sold over-the-counter product manufactured by the French company Boiron and marketed for flu-like symptoms. The full ingredient name on the label reads “Anas Barbariae Hepatis et Cordis Extractum,” which translates to “extract of Muscovy duck liver and heart.”
What the Preparation Actually Contains
The starting material is an autolysate, a mixture created by allowing the duck’s heart and liver tissue to break down in its own enzymes. That mixture is then diluted repeatedly using a method called Korsakovian dilution. Each step dilutes the solution roughly 1 to 100, and the process is repeated 200 times in sequence, producing what homeopaths call a “200K” or “200CK” potency.
The math behind this dilution is striking. The product label lists the active ingredient amount as 1×10⁻⁴⁰⁰ grams. To put that in perspective, the number of atoms in the entire observable universe is estimated at roughly 10⁸⁰. A dilution of 10⁻⁴⁰⁰ goes so far beyond that threshold that a typical dose is unlikely to contain a single molecule of the original duck tissue. What you’re actually swallowing is sugar: each 1-gram dose consists of 0.85 grams of sucrose and 0.15 grams of lactose.
Where the Idea Came From
The concept traces back to Joseph Roy, a French physician working during the 1917 influenza pandemic. Roy believed he had observed a strange oscillating microorganism in the blood of flu patients, which he named “oscillococcus.” He later reported finding the same microbe in the liver of a duck. No other researcher was able to confirm the existence of this organism, and modern microbiology does not recognize it. Still, the idea persisted in homeopathic tradition, and Boiron eventually developed it into the commercial product Oscillococcinum, which remains one of the best-selling homeopathic remedies worldwide.
What It’s Marketed For
Oscillococcinum is sold as a remedy for flu-like symptoms: body aches, headache, chills, fever, and fatigue. It is typically taken at the first sign of illness, with the claim that early use shortens the duration or severity of symptoms. In the United States, the product is labeled as a homeopathic medicine and is available without a prescription in most pharmacies and grocery stores.
What Clinical Evidence Shows
A Cochrane systematic review, considered the gold standard for evaluating medical evidence, assessed six studies on Oscillococcinum. Two trials involving 327 adults tested whether the product could prevent flu-like illness. There was no statistically significant difference between Oscillococcinum and placebo for prevention.
Four treatment trials, involving 1,196 teenagers and adults in France and Germany, looked at whether taking Oscillococcinum after symptoms started could speed recovery. Two of those trials (both rated as low quality) found a modest effect at the 48-hour mark: an absolute risk reduction of 7.7% in the frequency of symptom relief compared to placebo. A smaller effect was still visible at three days. By four and five days, there was no meaningful difference between the groups. The reviewers noted this pattern is consistent with the natural course of flu, which tends to improve on its own within a few days regardless of treatment.
The review’s conclusion was direct: there is insufficient good evidence to make robust conclusions about whether Oscillococcinum works for preventing or treating influenza. The limited positive findings came from low-quality studies, making the evidence “not compelling.” On the safety side, only one adverse event (a headache) was reported across all six studies, likely because the product contains nothing but sugar.
Regulatory Status in the U.S.
Homeopathic products occupy an unusual regulatory space. Under U.S. law, any substance listed in the Homeopathic Pharmacopeia of the United States qualifies as a “drug,” which means it’s subject to the same rules as conventional medications regarding labeling, safety, and marketing claims. However, homeopathic products have historically been sold without going through the FDA approval process that conventional drugs require.
The FDA has increasingly scrutinized this gap. In recent enforcement actions, the agency has stated that homeopathic drug products are “new drugs” that are “not generally recognized as safe and effective” and technically require FDA approval before being sold. No approved applications are in effect for these products. In practice, enforcement has been selective, with the FDA prioritizing products that pose direct safety risks (such as those containing toxic ingredients like belladonna) over sugar-pellet preparations like Oscillococcinum. But the legal position is clear: homeopathic drugs are not exempt from federal drug regulations, and the FDA does not verify their efficacy before they reach store shelves.
The Bottom Line on the Ingredient
Anas barbariae is Muscovy duck. The homeopathic preparation derived from it is diluted to such an extreme degree that no duck tissue remains in the final product. Each dose is effectively a gram of sugar. The clinical evidence for its effectiveness against flu is weak and based on low-quality studies, and the theoretical basis for why duck liver would treat influenza has never been validated by modern science.