Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. Its effects often last for 4 to 5 hours. Tadalafil belongs to a group of medicines called phosphodiesterase 5 PDE5 inhibitors. Alternatively, Cialis may be prescribed as an as-needed treatment for ED, to be taken before sexual activity. Do not stop taking tadalafil without talking to your doctor. The results showed the combination to be even more effective than either medication alone. Oral ED medicines might not work or might be dangerous if you also take any of the following: Nitrate medicines.heart attack symptoms – chest pain or pressure, pain spreading to your jaw or shoulder, nausea, sweating. Common tadalafil side effects may include: headache; flushing (warmth, redness, or tingly feeling); nausea, upset stomach; stuffy nose; or. muscle pain, back pain, pain in your arms, legs, or back. This is not a complete list of side. 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. Brand names for tadalafil include Cialis. The cost for tadalafil oral tablet 5 mg is around $27 for a supply of 90 tablets, depending on the pharmacy you visit. CVS Pharmacy, Target, WalMart Pharmacy, Duane Reade and 65, pharmacies nationwide. No manufacturer promotions could be found for this medication. Patient Assistance & Copay.