Carroll has suffered a new foot injury and is waiting to see a specialist to learn the extent of the damage.He has yet to play for West Ham since completing a club record £15million permanent move to Upton Park from Liverpool over the summer.
The England international scored seven goals in 24 Premier League appearances on loan at West Ham last season, but had been hampered by a heel injury.
That injury had prevented him from featuring in pre-season and manager Sam Allardyce had previously been hoping the 24-year-old would be fit to return before September.
However, Carroll only started full training again on Monday and he was immediately struck down by a fresh injury problem.
The club confirmed the setback in a statement and are now waiting for the former Newcastle forward to visit a specialist for a more detailed diagnosed.
"West Ham United can confirm that Andy Carroll suffered an injury to his right foot during his return to full training today," read a statement on West Ham's official website.
"Although it is in the same part of his foot as his previous injury, it is a new injury and therefore there will be no prognosis until he has seen a specialist.
"whufc.com will provide a further update when the relevant information is available."