Who should not take Cialis? It might work longer if you have mild to moderate erectile dysfunction. Common side effects may include: headache; flushing warmth, redness, or tingly feeling ; nausea, upset stomach; runny or stuffy nose; or muscle pain, back pain, pain in your arms, legs, or back. For treatment of pulmonary arterial hypertension: Adults—40 milligrams mg two 20 mg tablets taken once a day. However, because sexual stimulation is required to initiate the local penile release of nitric oxide, tadalafil’s inhibition of PDE5 will have no effect without sexual stimulation.tadalafil. erectile dysfunction (ED) benign prostatic hyperplasia, or BPH). Tadalafil (Cialis) is available both as brand-name and generic tablets. Common side effects of this medication include headache and indigestion. Tadalafil (Cialis) does interact with some medications. 1. Check your insurance coverage Since Cialis is available as a generic, many insurance plans now cover it (to varying degrees). Generally, Medicare does not cover Cialis, since it’s not considered medically necessary. AdSave on Health Products. Free 2-Day Shipping with Amazon Prime.