"Since tests haven't begun yet, we don't know what the ailment is," Tenzin Takla told The Associated Press. "Medical tests will begin on Friday."
The Dalai Lama's office in Dharmsala said Wednesday that the 73-year-old Tibetan spiritual leader was suffering from exhaustion and would cancel two planned international trips.
On Thursday, Takla said he was "admitted to hospital because of some abdominal discomfort."
The spokesman for Mumbai's Lilavati Hospital suggested the visit was an unscheduled one
"He comes every six months for a routine checkup. Around a month ago, a checkup was conducted and he was in perfect health," Mohan Rajan told The Associated Press.
The Dalai Lama will be under the care of senior surgeon Narendra Trivedi while at the hospital, Rajan said.
"There is no cause for concern," he added.
Takla said the Dalai Lama will spend some days in Mumbai, India's financial capital, to rest before returning to Dharmsala, where he has lived since fleeing Tibet in 1959 after an abortive uprising against China.
The Dalai Lama had just returned to India from an 11-day visit to France, capping an intense few months since riots against Chinese rule broke out in the Tibetan capital, Lhasa, and the subsequent government crackdown.
The spiritual leader spends several months a year traveling the globe to highlight the struggle of Tibetans for greater freedom in China and to teach Buddhism.
However, all of his, including the trips to Mexico and the Dominican Republic, said Thupten Samphel, the spokesman of the self-declared Tibetan government-in-exile.
Since the March outbreak of violence in Tibet,, blaming him for the recent unrest, which Beijing says was part of a campaign to split the Himalayan region from the rest of China.
The Dalai Lama has denied the allegations, saying that he only seeks greater autonomy for the Himalayan region to protect its Buddhist culture.