The generic name for Viagra is sildenafil citrate tablets and the generic name for cialis is tadalafil tablets, both of which have minor side effects that quickly disappear as the drug is metabolized. It is not possible to compare which side effect is greater. Both drugs belong to the class of phosphodiesterase inhibitors and are the first line of medication for the treatment of erectile dysfunction in men. The side effects of sildenafil citrate tablets are usually mainly headache, indigestion, facial redness, blurred vision and blue vision, and the medication should not be used after drinking alcohol. The side effects of tadalafil tablets are usually headache, indigestion, facial redness, back pain and muscle pain. Although the two drugs belong to the same type of medication, the incidence of side effects is different in the population, when patients take a drug with high side effects that can not be tolerated, you can change the other drug in time to reduce the side effects, and it is recommended to follow the doctor’s instructions for the use of medication.