The 19-year-old had only just come on as a substitute when he collided with team-mate Edson Alvarez at the London Stadium during an eventual 2-0 defeat by capital rivals Fulham.
Earthy fell to the ground awkwardly and it looked as if he had been knocked out cold, with medical staff and teammates rushing to his aid.
Having received on-field treatment for eight minutes, Earthy was carried off on a stretcher. He was conscious when he was taken out of West Ham's home ground in an ambulance some 20 minutes after the final whistle.
"West Ham United can confirm George Earthy will undergo an assessment in a London hospital this evening following the incident which saw him stretchered off during today's (Sunday's) Premier League fixture against Fulham," said a club statement.
"The midfielder -- who entered the field as a second half substitute to make his Premier League debut against the Cottagers -- was taken off in stoppage time."
West Ham manager David Moyes added: "I am really disappointed for George. He has been doing really well in training, done really well for the Under-21s.
"He started well with the ball, had some really nice touches. He is fine. It is a head knock. He is awake and has gone to hospital, we think he is OK at the moment. We all thought he had been knocked out but I don't know any more."
Fulham's win, built on two goals from Andreas Pereira, was a second blow to West Ham's hopes of European football next season following Thursday's 2-0 Europa League first-leg defeat at Bundesliga leaders Bayer Leverkusen,
Victory over Fulham would have lifted the Hammers to sixth in the Premier League table.
"I'm gutted, today was a great chance to go sixth with five games to go, what a great position to be in," said Moyes.
For Fulham it was a first win in four matches, and a first at West Ham since 2001.
"Great win for us, well played from ourselves and to be honest we deserved the three points," said Fulham manager Marco Silva.
"West Ham had a good chance to score but after that, we scored the first goal and started to control the game. Overall we scored twice but created more chances to score as well."
