Tadalafil is a medication used to treat erectile dysfunction in the male penis. Tadalafil is a phosphodiesterase-5 inhibitor, after taking the drug through selective inhibition of PDE5, enhancement of nitric oxide (NO)-cGMP pathway, elevated cGMP levels and lead to the relaxation of the cavernous smooth muscle of the penis, so that patients with erectile dysfunction to sexual stimulation to produce a natural erectile response. It should be noted that there is a possibility of headache, facial flushing, nasal congestion and runny nose and other reactions after taking the drug. It is forbidden to use it with nitrate drugs at the same time, so as to avoid life-threatening reactions of severe hypotension, and you should go to a professional hospital for consultation before using the drug. Tadalafil is also contraindicated in people who are allergic to any of the ingredients in this product, women, children and other groups.