Viagra generally refers to sildenafil citrate, which requires sexual stimulation for the drug to take effect, and an increase in penile hardness after erection compared to before indicates that the drug is taking effect.
Sildenafil is able to stretch the smooth muscles of the corpus cavernosum, increasing blood flow to the penis during sex. This product needs to be taken as needed before sexual activity, and sexual stimulation needs to be present after taking the drug in order for it to take effect. After the drug takes effect, you may feel that the hardness of the penis has increased compared to the previous one, if the change in hardness is not obvious, you can increase the dosage appropriately or consult your physician.
Side effects of this drug include headache, rash, visual abnormalities, flushing, dizziness, indigestion, etc. It is contraindicated for those who are allergic to this product and cannot be used together with nitrate.
It is recommended to consult the relevant physician before using the drug, and should not take the drug blindly.