Up to half a million disabled people and their families could be worse off under the new system of Universal Credit once it is fully implemented, according to a report.
It suggested some people might even be forced out of their homes as a result of the changes.
An inquiry headed by former wheelchair athlete Baroness Tanni Grey-Thompson said several "key" groups would lose out under the Universal Credit, which will start to replace much of the benefits and tax credits system from next year.
The study used research showing that once the changes are fully in place, 100,000 disabled children stand to lose up to £28 a week, 230,000 severely disabled people who do not have another adult to help them could receive between £28 and £58 a week less, and up to 116,000 disabled people who work could be at risk of losing around £40 a week.
The report said the impact of the cuts in support for disabled children could be "extremely severe" for families currently receiving the mid-rate "care component" of the Disability Living Allowance (DLA), a payment made where a child can be severely disabled but does not need care overnight.
Of those families affected, one in 10 expressed fears that they could no longer afford their own home, while two thirds said they would have to cut back on food, and more than a half said it would lead them into debt.
In some of the most severe cases, some families said the changes to support for disabled children could result in their children having to be placed in full-time residential care.
The report said 83% of those eligible for the severe disability premium (SDP), which will be abolished under the changes, reported that a reduction in benefit levels would mean they would have to cut back on food and 80% said they would have to cut the amount they spent on heating.
The changes start to come into force from October next year and current benefit claimants who move on to Universal Credit will not see an immediate reduction in their payments.
But they will have their level of benefit frozen, with no increases to take into account rising prices, campaigners said, and they may see their support cut immediately if their household circumstances change.
The report, Holes in the Safety Net: the impact of universal credit on disabled people and their families, had the backing of The Children's Society, Citizens Advice and Disability Rights UK and drew on research from these bodies.
Lady Grey-Thompson, who shares the title of Great Britain's most successful female Paralympian with cyclist Sarah Storey, said the findings of the report did not make "easy reading".
"The clear message is that many households with disabled people are already struggling to keep their heads above water," she said.
"Reducing support for families with disabled children, disabled people who are living alone, families with young carers and disabled people in work, risk driving many over the edge in future."
A spokeswoman for the Department for Work and Pensions (DWP) said savings from abolishing the adult disability premiums and changes in the child rate would be "recycled" into higher payments for more severely disabled people.
She said the report was "highly selective and could result in irresponsible scaremongering", adding that Universal Credit would provide greater incentives for people - including disabled people - to try out work, and would reduce the financial and administrative barriers to work that exist in the current system.