Apcalis has been studied extensively in clinical trials, with over 7,450 people having been evaluated. Based on these studies, common Apcalis 20mg side effects, occurring in more than 2 percent of people, include:

• Headache — up to 17% of people
• Indigestion, known as dyspepsia — up to 9% of people
• Back pain — up to 5% of people
• Facial flushing — up to 8% of people
• Nasal congestion — up to 9% of people
• Muscle pain (known as myalgia) — up to 4% of people
• Pain in the arms or legs — up to 8% of people.