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space motion sickness (SMS)

A condition similar to ordinary travel sickness, produced by confusion of the human vestibular (balance) system and the absence of a gravitational vertical; it is also known as microgravity nausea. About one-third of Apollo crewmembers reported some level of SMS, rising to 60% on the longer-duration Skylab missions. During Space Shuttle flights the incidence of SMS in first-time astronauts has also been about 60%. Treatment with such medications as intramuscular promethazine (Phenergan) has been effective, and the nausea tends to wear off two to three days into the flight.

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