There are many works and franchises where one or more factions or species have achieved Faster-Than-Light Travel, using many different kinds of phlebotinum. However, that doesn't necessarily mean that such travel is safe, or without consequences. The means used can mess with or even break the fundamental nature of reality, and the minds and bodies of those who go through it often aren't able to properly process the experience. Thus, when they make an FTL transit, they will feel some form of distress. They may suffer from headaches, nausea, dizziness and other physical ailments, have hallucinations, or even run the risk of more serious issues like going insane or even dying. As well as during the trip, there's also the chance that these conditions can linger even after the vessel transits back into realspace. Methods can be taken to mitigate these effects, but they're usually specific to the nature of the setting and aren't always completely effective.
If Hyperspace Is a Scary Place in the setting, this can directly result from traveling through it. The effects can be a Brown Note if they're severe enough.
Compare Cryo Sickness, as people who go into cryosleep or other means of stasis to survive interstellar travel may become ill (or worse) after awakening. Also compare Teleportation Sickness and Ludicrous Speed.
- I'm Nobody: Normally this trope doesn't apply, as the only vehicles capable of FTL travel (a.k.a. spaceships) are equipped with technology that completely dampens the impact of accelerating to FTL speeds. However, when the Normandy crew is forced to use the Mass Effect relay (an FTL accelerator) while riding a land vehicle, they come out from the other end feeling like they've been compressed from all sides. It was a miracle that didn't kill them.
- Airplane II: The Sequel: Parodied. Ted Striker takes the shuttle to "point five Worp" to try to get back to the Moon before the shuttle's air supply runs out. This has the side effect of turning the passengers into mannequins wearing Nixon masks.
- Event Horizon: Event Horizon uses a space-folding drive for FTL travel, as explained by its creator, Dr. Weir. When the crew of Lewis and Clark finally discover the ship's log, they see Event Horizon's crew preparing for their first jump. The log then cuts to the crew slaughtering each other in both a figurative and literal orgy of horrifically gory violence. It's slowly revealed that the ship traveled through a hellish alternate dimension which drove the crew utterly insane and corrupted the ship itself.
- Guardians of the Galaxy Vol. 2: Making hyperspace jumps is relatively safe, but making numerous jumps in short succession, such as the 700 jumps that Rocket, Yondu, and Groot must do to cross the galaxy in order to get to Ego, takes a toll on them. Their bodies, and those of the other people on the ship, physically distort and stretch similar to spaghettification, and when they finally reach Ego, they fall to the deck in exhaustion and Groot throws up.
- Remaining conscious during FTL travel through Jump-space causes extreme psychological stress in humans, who must place themselves in drug-induced sleep to avoid it. A small number, however, can stay alert without ill effects, and manage to adjust to the strange reality; they are known as "Nightwalkers", and are seen with a fair degree of paranoia by others.
- Carrera's Legions: it's noted that when a ship goes through the wormhole connecting Earth to Terra Nova, it can cause a feeling of extreme nausea for some people when they're awake. The feeling passes in a second or two, but for those who are experiencing this sickness, those seconds seem to last much longer.
- In the Chanur Novels, most of the oxygen-breathing alien species experience their own issues with Jumps. The hani become paralyzed and their minds enter a dream-like state, and after coming out of jump are groggy and shed horribly, though Nightwalkers are not unknown among their species. Mahendo'sat are implied to react similarly to hani. The stsho take Jump even worse than humans, the shock kills them without sedation. The kif, and other animals from their homeworld, are entire species of Nightwalkers. Nobody knows how the methane-breathing species handle Jumps, but most speculate they're Nightwalkers given that they occasionally appear to maneuver mid-Jump.
- Isaac Asimov:
- "Escape!": The first ship capable of interstellar travel can jump to other solar systems. Because of the way the ship's drive works, anyone on board temporarily dies during the jump and experiences hallucinations of after-death experiences. When the jump concludes, the people come back to life.
- "Risk" (in the same continuity as "Escape!"): Any creature traveling with the prototype hyperspace drive becomes a mindless husk.
- The Gap Cycle: The jump-style "gap drive" induces bursts of homicidal psychosis in a tiny minority of people who go through FTL transit, which led to the destruction of several ships until the problem was tracked down; sufferers of "gap sickness" are treated by receiving zone implants, neuro-electrical devices which can be activated to place them into hypnagogic trances, neutralizing them during the transition and afterwards. Unfortunately, people with zone implants can also be controlled remotely, which kicks the plot off when heroine Morn Hyland (who discovers too late on her first star cruise that she is one of the vulnerable few) is captured by space pirate Angus Thermopyle and implanted against her will....
- Hammer's Slammers: FTL travel is done by a system called the Transit drive, which makes several small jumps but whose mechanics are never fully explained. Since the human body wasn't intended to travel faster than light, starship crews experience fatigue and disorientation during a jump, and suffer cluster headaches afterwards.
- The Hitchhiker's Guide to the Galaxy: The sensation of entering hyperspace is described as feeling like getting turned inside out at the navel. The experimental Infinite Improbability Drive has even more esoteric effects, such as temporarily turning the passengers into penguins.
- Hyperion Cantos: Traveling with a Hawking Drive causes severe hallucinations among other things, which is why most travel is conducted in cryosleep. The Ousters have modified ships that block the side effects.
- Lensman: The Inertialess Drive is the primary means of FTL travel; it leaves people feeling space-sick, although the feeling can be adjusted to. However, travel by hyperspatial tube causes a sickening sensation that no one ever becomes accustomed to.
- Loar: Jumping through an hyperspace "node" causes unconsciousness; one of the factions uses a selective breeding program to get pilots with the a short wake-up time, hoping to field assault fleets that can wake up fast enough not to be shredded by defenders when they come out of the node.
- The Mote in God's Eye: Starships travel between solar systems by using the Alderson Jump point that corresponds to the star they wish to go to. After the ship jumps and arrives at its destination, everyone on board suffers from confusion and disorientation for a short time. The effect also causes all operating automatic equipment, including computers, to activate randomly after a jump. Such equipment is therefore shut off pre-jump to prevent problems. This turns out to be an important plot-point when it's learned that Moties suffer much more from this effect than humans do.
- The Sirantha Jax Series: Travel through grimspace is much faster than travel through "straight space", an earlier method of Faster-Than-Light Travel, but requires a person with the "J-gene" to be plugged into the ship with a Brain/Computer Interface in order to read beacons left by a Precursor race. These "Jumpers" are prone to a disease called Navigator Burnout Syndrome that causes brain lesions to develop with successive jumps, until eventually they jump and their minds don't come out of grimspace—normally not much later than age 30. Title character Sirantha Jax has lasted far longer than Jumpers usually do, because she was conceived in grimspace, which causes NBS to affect other parts of her body that can heal from the damage.
- The Stars Are Cold Toys: Members of every alien species who have ever tried traveling faster-than-light either died or went incurably insane in the attempt. The only exception are, for reasons unknown, the humans, who have therefore been pigeonholed into the role of galactic taxi drivers almost as soon as they made contact with other sentient species (who have to be deep-frozen to survive FTL trips). The plot of the first book is kicked off when a human pilot returning to Earth discovers an alien stowaway on his ship who didn't go insane during the trip out of cryo.
- Strata: Travelling FTL above a certain speed causes "soul-lag" — some part of a sapient mind has a fixed maximum speed, and if you exceed it you end up experiencing apocalyptic despair until you reach your destination and your soul has time to catch up with you.
- Uncharted Stars. When a starship begins a hyper jump, passengers who are properly prepared and bedded down only feel a sickening twist. If not so prepared, they suffer serious physical trauma, including unconsciousness, bleeding in the mouth, and intense pain throughout their bodies.
- Vorkosigan Saga: Going through one of the "wormholes" which form the setting's Portal Network seems to cause most people to experience at least momentary dizziness. There is also a more serious malady called "jump sickness", which seems to be something like seasickness or airsickness, including varying degrees of personal susceptibility.
Ekaterin: Oh, no, sir, do you meant to say you are dragging that poor woman through five wormhole jumps from Barrayar to Komarr for me? She gets so jumpsick!
- Babylon 5: In The Lost Tales, Sheridan is being interviewed by a newsreporter aboard a starship that uses a newly-developed FTL method involving travelling through "quantum space". Sheridan mischievously only informs the reporter at the last minute that it can cause nausea in people, and it's implied that she pukes on camera.
- Battlestar Galactica (2003): Implied in the pilot when Callie goes into a fetal position as Galactica begins to jump and mutters that she hates this part. The concept doesn't seem to have survived past the pilot.
- BattleTech: Transit Disorientation Syndrome, or "jump sickness", is a condition that afflicts some people after a K-F jump. Symptoms include headaches, nausea, irritability, disorientation, and diarrhea. They typically only last for a few hours, but if the person undergoes a second jump while still experiencing symptoms, they can be incapacitated for as long as a week. Suffering from this condition doesn't really impact a mechwarrior's career in any way, but you can't serve on a jumpship or dropship crew or as an aerospace fighter pilot.
- Warhammer 40,000:
- Imperial vessels must traverse the nightmare hellscape of the Warp in order to make interstellar trips. While they use Gellar fields to keep out the daemons and raw stuff of Chaos that permeates the Warp, their presence and influence still affects the ships' crews to a small degree. This routinely causes them to feel intense paranoia, experience visual and auditory hallucinations, and/or have terrifying nightmares. Those who are particularly sensitive or weak-willed may completely snap; some mutilate themselves or even commit suicide to escape the horrors they've experienced, while others may attack their fellow crewmates. In the very best conditions transferring from the Warp to realspace and vice-versa causes intense nausea.
- Other factions that use the Warp (orks and Chaos mostly) have no such issues, seeing it as enjoyable or just another day on the job.
- Outsider: FTL travel is done using hyperspace jumps, and Jardin is shown going through a jump starting in #215. The experience isn't pleasant; he notes that the vibration can crack your teeth, time dilation can cause people to experience disturbing visions, and you feel like you have a serious hangover afterward. He also wryly notes that people not on duty should avail themselves of recreational drugs to distract them from the experience. Interestingly, the Loroi that are accompanying him don't seem to be affected by the jump at all.
- Ben 10: Alien Force: In "War of the Worlds Part 2", in order to reach the Highbreed homeworld, Ben's team travels through an interstellar jump-gate that converts users into faster than light tachyons and transmits them to the other side. Ben (as Brainstorm) promptly throws up at the end of the journey.
- I Am Weasel: Played for humor in "The Magnificent Motorbikini". Weasel and Baboon are riding on the titular contraption as it passes the speed of light, and other speeds as well.
Weasel: We just passed the speed of smell! Next is the speed of light!
Baboon: What are after speed of light?!
Weasel: Any third-grader knows that! After the speed of light...
[the bikini's speed increases and they're suddenly morbidly obese]
Weasel: Is the speed of heavy.
- Steven Universe: Played with. Gem technology makes FTL travel perfectly safe, but in "Adventures in Light Distortion", Pearl doesn't give Peridot the time to work on the Ruby ship's gravity engine before she, Steven and the Crystal Gems leave in it. The gravity engine later turns out to be what allows Gems to maintain their proper physical forms in the ship while travelling. So, while Steven is fine, with the ship not keyed to their correct appearances, the Gems become distorted and things only worsen as Steven fiddles with the controls to return them to normal.