Former US President George HW Bush is said to be responding to treatment for an infection that spread to his blood.
The 93-year-old was admitted to hospital on Sunday, only a day after his wife Barbara's funeral.
Family spokesperson Jim McGrath said the former president appears to be recovering.
George HW Bush suffers from a form of Parkinson's disease, and he uses a wheelchair.
He has been admitted to hospital on several occasions in recent years.
The 41st US president attended his wife's funeral over the weekend, along with his son George W Bush.
Bill Clinton and Barack Obama were also among those in attendance, while current First Lady Melania Trump also travelled to Texas for the funeral.
1 of 2: Final photos from the funeral of former First Lady Barbara P. Bush. (Credit: @PaulMorsePhoto - Office of George H. W. Bush) pic.twitter.com/r9ElE3Av56
— Jim McGrath (@jgm41) April 22, 2018
George HW and Barbara Bush were married for 73 years before her death on April 17th, aged 92.
At the funeral, the former president wore a pair of socks with a book design to honour his wife's "commitment to family literacy".
The socks worn by the 41st President of the United States of America at today’s funeral for former First Lady Barbara Bush. pic.twitter.com/12libHt1Jv
— Jim McGrath (@jgm41) April 21, 2018
