Jacob went to his room, bringing a glass of water and the tablets with him. He took one, and then waited for it to take effect.
It didn't take as long as he expected. After a few minutes, his skin felt sort of itchy, his clothes irritating to the touch. He locked the door to his room and decided to take a look at his body, undressing and looking at himself in the mirror.
He gasped. Most of the hair on his body had vanished besides that on his head and crotch. His face looked subtly different, more feminine and softer. His hair was gently extending down to his shoulders, and seemed to be going further still. Then he felt an unfamiliar feeling in his chest. Looking down, he saw his nipples perk up, and whimpered as they became larger and more sensitive. As he breathed, flesh started to form around them while the rest of his body turned slimmer and more petite. His nipples swelled too, widening and softening, and he started to rub and pinch them, moaning softly as he did so.
Suddenly another strange feeling affected him, this time in his crotch. He yelped as his testicles pulled up inside him, and his scrotum moved up to become almost flush with the rest of his crotch. He felt his testicles reshape themselves into ovaries and connect to something forming in him, which he soon realized was his womb. But what most surprised him was when he noticed his penis beginning to shrink, pulling back inside him. He was surprised how good it felt- it was like as it shrank, the sensations got more concentrated and intense around what was still there. And since he could feel the skin of his crotch reshaping into lips and a passage forming inside, the idea of being fucked was becoming more and more appealing.
Finally, he... no, she... felt the changes finish, as the penis finished transforming into a clitoris and a vaginal slit formed from her crotch. When she looked in the mirror properly, she saw a woman- one who looked a lot like Jacob, but unmistakably a woman. Jade, she thought. That'd be a nice name.