A NASA astronaut who was hospitalized upon return from the International Space Station for an unspecified medical condition was released Saturday in "good health," the US space agency said.

The four-member Crew-8 mission splashed down off the coast of Florida early Friday after nearly eight months aboard the orbital laboratory.

NASA did not reveal which of the astronauts was hospitalized nor the reason, citing medical privacy.

However, it said in a blog post that the crew member has returned to the Johnson Space Center in Houston "in good health and will resume normal post-flight reconditioning with other crew members."

On its way back to Earth, the SpaceX Dragon executed a normal re-entry and splashdown, and recovery of the crew and spacecraft was without incident, NASA said.

But during routine medical assessments on the recovery ship, an "additional evaluation of the crew members was requested out of an abundance of caution," it added without elaborating.

NASA astronauts Matthew Dominick, Michael Barratt, and Jeanette Epps, and Roscosmos cosmonaut Alexander Grebenkin were all flown to Ascension Sacred Heart Pensacola.

Three were subsequently released, while one remained at the hospital "under observation as a precautionary measure."