It’s available in 50 mg, mg, and mg tablets. FDA encourages anyone aware of a serious side effect, including consumers or patients, to make a MedWatch report. When oral medications might not be safe Check with your health care team before you take any medicine for erectile dysfunction. This medicine works best when you take it on an empty stomach an hour before sex. Your doctor will discuss the best treatment plan for you.The four main medicines taken by mouth for erectile dysfunction are: Avanafil (Stendra). Sildenafil (Viagra). Tadalafil (Cialis). Vardenafil. These medicines are called PDE5 inhibitors. They enhance the effects of a chemical the body makes that relaxes muscles in the penis, called nitric oxide. Viagra is a well-known, branded and common erectile dysfunction (ED) treatment for men. It’s available on prescription through our Online Doctor service. The original brand that’s effective for % of men. Works in 1hr and lasts hrs. 25mg 50mg mg. Tadalafil is a medicine used to treat erectile dysfunction (ED, also called impotence) and problems with urination caused by an enlarged prostate (benign prostatic hypertrophy or BPH). It is sometimes known by its generic name tadalafil, and sometimes known by its trade name, Cialis. There are also other brands of this medicine available.