Emling S. After taking a single tablet, some of the active ingredient of Cialis remains in your body for more than 2 days. It is not possible to determine whether these events are related directly to the use of PDE5 inhibitors or to other factors [see Adverse Reactions 6. How can I buy tadalafil? The as-needed dose is usually 10 mg but can range from 5—20 mg.The drug comes in low-dose versions that can be taken daily. This means you can have sex at any time, rather than needing to take a pill from time to time as needed like other ED brands. The starting dose for daily-use Cialis is milligrams (mg). If that doesn’t work, you can increase your daily dose up to 5 mg. • The recommended starting dose of CIALIS for once daily use is mg, taken at approximately the same time every day, without regard to timing of sexual activity. • The CIALIS dose for once daily use may be increased to 5 mg, based on individual efficacy and tolerability. CIALIS for Once Daily Use for Benign Prostatic Hyperplasia. The most common side effects with Cialis are: headache, indigestion, back pain, muscle aches, flushing, and stuffy or runny nose. These side effects usually go away after a few hours. Men who get back pain and muscle aches usually get it 12 to 24 hours after taking Cialis. Back pain and muscle aches usually go away within 2 days.