There are two different dosages of this drug: Chewable and sublingual. The chewable version can be taken without water and starts working more quickly, while the sublingual one is a fast-acting pill. vidalista belong to the same group of medications: PDE5 inhibitors. They help you achieve a healthy erection by increasing the blood flow to your penis and making it firmer. They are also known to have fewer side effects than Sildenafil. However, they may cause vision problems. If you have eye problems or blood vessel disorders, talk to your doctor before taking vidalista 20.