When Seth Brundle makes a huge scientific and technological breakthrough in teleportation, he decides to test it on himself. Unbeknownst to him, a common housefly manages to get inside the device and the two become one.
This movie contains 46 potentially triggering events.
Not in a direct physical context, but brundlfly's relationship with Veronica takes on an abusive tone towards the end (kidnaps her and tries to force her to "meld" with him) which could definitely be triggering
A monkey dies when it gets teleported and turns inside out. Ive only seen the 1 monkey die. And a deleted scene a cat and a monkey gets emerged together and is deformed. And then gets killed.
If you consider the baboon used in experiments to be a pet, then yes. The first baboon to be teleported gets turned inside out and dies shortly thereafter. The second baboon survives in the theatrical cut. However, there's a deleted scene where the baboon is fused with a cat, and the resulting monstrosity is beaten to death with a pipe.
Body horror is central to the film's premise of undergoing a slow, irreversible, uncontrollable transformation. Plenty of gruesome details, such as body parts mutating or falling off, are clearly shown.
Pretty infrequent, not necessarily "excessive", but the gore shown is pretty gnarly; particularly a broken bone during an arm wrestling scene a little after midway-through
The main character, Seth Brundle, dies at the very end. After mutating into a half-fly, half-man and being accidentally fused with a broken telepod, his body is mangled beyond repair. He begs for death by holding the barrel of a shotgun to his head. His lover reluctantly obliges his last request.
Seth hooks up with Tawny. It's a little unclear if that's cheating or if his "plasma pool" speech was him intending to break up with Veronica and then moving on to Tawny, but from the way he reacts when Veronica catches him, I think he was cheating on her
Not a real-world mental illness per se, but Seth Brundle clearly loses his sanity as his mind merges with the mind of the fly. He's fully aware that this is happening, but there's nothing he can do to stop his mental deterioration.
Not in the cutting sense. However - and this doubles as a warning for hand/finger gore - in a scene that takes place in his bathroom, Seth discovers something wrong with his fingers that leads to him removing his own fingernails.
There's definitely a lot of expected gross noises accompanying Seth's transformation, mainly squishy wet sounds. I personally found it hard to listen to at times so it might be a trigger for someone else as well.
[SPOILERS] There is a scene that shows the actual procedure of an abortion right up to the removal of the fetus, but this ends up being a dream. The woman tries to go through with it again in real life, and is in the operating room when they are interrupted.
According to the director, Seth loses his virginity the first time he sleeps with Veronica, but in the film it's not brought up that it's his first time
Veronica wants to get an abortion and Seth objects, not because of any anti abortion bias but because he views the baby as the only remnant of his humanity.