Cialis (tadalafil) can be prescribed for a number or conditions, but is most often used to treat erectile dysfunction. Cialis is the medicine that provides for the longest sexual ability – after taking your dosage you will be able to perform sexually during the next 36 hours, although this period may vary slightly from person to person. Usually the effects of Cialis are the strongest during the first 12 hours from the moment you take it. In most cases the patients that are treated for the first time are prescribed 10 mg of this medicine, but this can be different if your health care provider thinks you need a higher or lower dosage of this medicine. Cialis should be stored in a dark and cool place where people to whom it was not prescribed will not be able to access it. In people with kidney or liver disease Cialis should be used with special caution. It’s generally recommended to start with the 5 mg. dosage and the patient is expected to observe the guidelines of the doctor to benefit from the treatment.