Fosfomycin 3gm sachet: treat bladder infections https://www.dosepharmacy.com/fosirol-powder-3g-sachet Before starting to use fosfomycin, read the Patient Information Leaflet if your pharmacist has one. Ask your physician or pharmacist if you have any queries. As prescribed by your doctor, consume 1 packet (sachet) of this medication orally each time. Before using this medication, mix it with water. In a half glass (4 ounces or 120 millilitres) of cold water, add the contents of 1 packet (sachet), and swirl to combine. Use only cold or warm water. Consume the entire mixture at once.