Is it permissible to use medication to increase penis size and length? And is this considered an unlawful alteration of God's creation, as mentioned in the verse, "and they will surely alter God's creation"?

Changing Allah's creation is forbidden by the Qur'an and Sunnah (definition). Allah narrated Iblis's statement: "And I will surely command them, so they will change the creation of Allah." This includes castration, plucking eyebrows (namṣ), tattooing (washm), teeth filing (washr), teeth gapping (taflīj), and hair extensions. Human intervention in these matters is forbidden except out of necessity.

Increasing the size of the penis surgically is not permissible except out of necessity, such as impotence (al-'unna). However, if it is done by taking medication, human intervention is not involved, and it is permissible as long as it does not lead to harm.