Forzest 20 mg, which contains tadalafil (the same active ingredient as in Cialis), can cause side effects, although not everyone experiences them. Tadalafil is a PDE5 inhibitor used to treat erectile dysfunction (ED) and sometimes benign prostatic hyperplasia (BPH). It works by increasing blood flow to the penis, helping to achieve and maintain an erection when sexually aroused. Common Side Effects of Forzest 20 mg (Tadalafil): These are the most frequently reported side effects, but they are usually mild and temporary: Headaches: One of the most common side effects. If the headache becomes severe or persistent, consult a doctor. Indigestion (Dyspepsia): You might experience stomach discomfort, bloating, or acid reflux. Back Pain: Some people Forzest 20 mg  muscle aches, particularly in the back, which usually goes away after a few hours. Flushing: A warm sensation or redness in the face, neck, or chest can occur due to increased blood flow. Nasal Congestion: Some individuals may experience a blocked or runny nose. Dizziness or Lightheadedness: This may happen when standing up quickly (due to a temporary drop in blood pressure). Sinusitis: Symptoms of sinus infection, like stuffy or runny nose, can sometimes occur. These side effects are generally mild and go away on their own as the medication wears off. Less Common, But More Serious Side Effects: While rare, some individuals may experience more severe side effects: Vision Changes: Blurred vision or seeing a blue tinge to objects can be a rare side effect. If you experience sudden loss of vision or changes in vision, seek medical help immediately.