Herbs are known for their antiviral properties, and can be used to help fight off viral infections. Some of the most common herbs used to kill viruses include garlic, ginger, echinacea, and elderberry. Garlic is thought to have anti-viral activity due to its sulfur compounds, which have been shown to inhibit a variety of viruses. Ginger is also believed to have anti-viral properties, and has been used to treat colds, flu, and other respiratory illnesses. Echinacea is an herb commonly used for its immune-stimulating properties, and may help strengthen the body's ability to fight off viral infections. Elderberry is also widely used for its antiviral properties, and is believed to be effective against the flu virus. In addition to these herbs, several other medicinal plants have been found to have anti-viral properties, including licorice, astragalus, and cat's claw.