generic pills online order cialis online Upon purchase from 50 tablets we will deliver your order free of charge buy viagra online best price viagra buy viagra online best price cialis buy cialis online How Common Is Erectile Dysfunction? Failure to achieve an erection less than 20% of the time is not unusual and treatment is rarely needed. Failure to achieve an erection more than 50% of the time, however, generally indicates there is a problem requiring treatment. What is tadalafil (Cialis)? Tadalafil (Cialis) is the third oral medicine approved by the U.S. FDA for the treatment of erectile dysfunction. Like sildenafil (Viagra) and vardenafil (Levitra), tadalafil inhibits PDE5 (as described earlier). Other hormone levels: Measurement of other hormones beside testosterone (luteinizing hormone (LH), prolactin level, and cortisol level) may provide clues to other underlying causes of testosterone deficiency and erectile problems, such as pituitary disease or adrenal gland abnormalities. Thyroid levels may be routinely checked as both hypothyroidism and hyperthyroidism can contribute to erectile dysfunction.