The Alzheimer’s Society estimated that last year there were up to 54,000 potentially avoidable emergency admissions in England for patients with dementia.
The charity said the figure has increased substantially over the last five years - coinciding with cuts to social care.
Meanwhile a poll of 113 of paramedics found that one in five said they see the situation first hand “every day”.
And half said they see it each week, according to the survey by the College of Paramedics.
Cuts to care services can mean that problems that start off small can escalate into serious issues, the charity said.
For instance, if a person with dementia is not receiving the appropriate support at home then they could become dehydrated which could lead to a urinary tract infection (UTI).
The charity sent Freedom of Information requests to 65 major English hospitals to ask about emergency admissions for dementia patients due to potentially avoidable issues - including dehydration, delirium, UTIs, chest infections and falls.
They found that the number of admissions for over-65s with dementia rose from 31,000 in 2011/12 to 54,000 in 2016/17.
It said that in a similar time period there has been a 40% cut to council budgets, with local authorities responsible for social care funding.
The Alzheimer’s Society said that the overworked and underpaid care workforce lacks time and training which means people with dementia are not getting the support they need.
“Successive governments have shirked the issue of our threadbare social care system,” said the charity’s chief executive Jeremy Hughes.
“Starved of the care they need, people with dementia end up in A&E as a last resort, disrupting their home life and forcing them to struggle in crowded hospital wards. It shouldn’t and needn’t be like this.”
Commenting on the analysis, Izzi Seccombe, chairwoman of the Local Government Association’s Community Wellbeing Board, said: “This report is further stark evidence of the crisis in adult social care which cannot be ignored.
“To help reduce pressures on the NHS, social care needs to be given parity with the health service and councils need urgent funding to invest in effective prevention work to reduce the need for people to be admitted to hospital in the first place.
The Government intends to publish its social care green paper later this year.
A Department of Health and Social Care spokeswoman said: “No-one with dementia should have to go into hospital unnecessarily and we’re determined to continue to drive up standards of care.
“We are already ranked as one of the best in Europe for our approach to dementia and have invested £50 million to make hospitals and care homes dementia-friendly.”
Labour’s shadow social care minister Barbara Keeley said: “This report is a devastating analysis of the social care crisis created by this Tory Government, which is the result of eight years of swingeing cuts to council budgets.
“The Tories are failing people with dementia by kicking social care funding into the long grass.”