Cialis is a drug that is used to treat erectile dysfunction. It is a phosphodiesterase type 5 inhibitor. The drug works by relaxing the muscles in the blood vessels in the penis, allowing more blood to flow into the penis and making it easier to get and maintain an erection, read more. Cialis can be taken with or without food. Cialis should not be taken more than once a day. Cialis can be bought online from a variety of online pharmacies. Some online pharmacies will require a prescription, while others will not. Cialis can also be bought without a prescription in Netherlands from some online pharmacies. Cialis should not be taken by women or children.