When applied to the skin, elderberry is effective at treating wounds. In many countries, including Germany, elderflower is taken orally to treat respiratory illnesses such as colds and flu. Some evidence suggests that chemicals in elderflower and elderberries may help reduce swelling in mucous membranes, such as the sinuses, and help relieve nasal congestion. Elder may have anti-inflammatory, antiviral, and anticancer properties. Dosage is easy, just consume jam or wine made from elderberries. But be aware that the raw berries are mildly toxic, and they may have drug interactions with diuretics (water pills), diabetes medications, chemotherapy, laxatives, theophylline (TheoDur), or drugs that suppress the immune system.