People with HIV and Aids face living in poverty as a result of their diagnosis, experts claim.
People with long term health problems can be hit by depression
The charities Crusaid and the Terrence Higgins Trust said the problems they face can range from losing their job or their home to debt and depression.
They warn that increasing numbers of HIV positive people are forced to apply for financial support.
The charities say small but significant changes to the law and government regulations could reduce the problem.
A report by the charities looked at data and case studies from the Hardship Fund, which has helped around a quarter of HIV positive people in the UK.
It found there had been an unprecedented demand for assistance from the fund. In 2002 it paid out almost three quarters of a million pounds to people living in poverty after being diagnosed with HIV, up 47% since the year 2000.
Just over 3,180 people received awards last year, compared to 1,960 two years earlier.
The report found that the average weekly income of people applying to the fund fell from £93.79 in 1999 to £65.08 in 2002.
Figures for 2003 so far appear to show the amount has fallen again to £57.21 per week.
The report says other problems HIV positive people face include domestic violence, depression and difficulty in coping.
Crusaid and the Terrence Higgins Trust (THT) called on the government to set up a cross-departmental task force to tackle the rising epidemic of HIV and sexual ill-health in the UK, including measures to tackle discrimination against people with HIV and those communities most at risk.
Other recommendations included reviewing the benefits system for people with intermittent or relapsing medical conditions like HIV, good practise guidelines for employers with HIV positive staff and better support from health workers for people newly diagnosed.
The charities also said local authorities and housing trusts should treat HIV-related and homophobic abuse and violence with the same seriousness as racist abuse and violence.
Steven Inman, head of grants and projects at Crusaid and manager of the Hardship Fund, said: "The most productive people in our economy - those who we would normally expect to earn money for themselves through work - are now in a poverty trap as a result of repeat bouts of ill-health and the inability to find work because of stigma and discrimination.
"The data shows conclusively that people living with a positive diagnosis are experiencing worsening levels of poverty and, as a result, are turning to the fund in ever greater numbers."
He added: "The pattern of HIV and Aids in this country is changing. Today we are seeing more and more people contracting HIV alongside high levels of complacency and ignorance about the need for safer sex.
"New applicants for help often lack any substantive income or savings and are having to turn to the Fund to help pay for the most basic of necessities."
Lisa Power, head of policy at Terrence Higgins Trust, added: "Much of the poverty trap that people with HIV fall into could be stopped by small but significant changes to the law and government regulations.
"We call upon the government to make these changes, outlined in the report, to help people with HIV to help themselves."