Colds and flu can be prolonged if you take medications with inappropriate drinks, pharmacist Yalanci told RIA Novosti. During the cold season, many people constantly drink tea and may take medications with it, without thinking that they thereby reduce the effectiveness of the active ingredients. And if you drink coffee instead of tea, the additional load on the heart and nervous system increases. Citrus juices affect liver enzymes and, consequently, the concentration of the drug. Milk contains calcium, which interferes with the absorption of antibiotics. And St. John's wort in herbal tea helps remove the active substances of the drug. Therefore, the best option is to take your medications with 150-200 milliliters of clean room temperature water.