Cialis is an orange-yellow, film-coated tablet in the shape of an almond. Cialis will be available as oral tablets in 5mg, 10mg and 20mg strengths. PDE5 inhibitors only work in the presence of nitric oxide, which is released during sexual arousal, so you will need to be aroused for Cialis to work. Cialis side effects can happen and the drug can interact with other medications causing side effects such as headache, stomach upset, muscle pain, stuffy nose, flushing or dizziness. No, Cialis does not lose potency over time.Save ? Was ? 4 UNI | ? per 1UNI. Save 10 percent on Cialis Together 10mg Tablets Tadalafil 4 Tablets. Free next day delivery on selected medicines when you use code HEALTHFNDD, order by 8pm – online only. Helps you get and maintain an erection when you need it. Effective up to 36 hours. 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. headache. indigestion. back pain. muscle pain. flushing. stuffy nose. Patients who get back pain and muscle aches usually get them 12 to 24 hours after taking Cialis and these usually go away by.