A group of leading charities in the UK overstated the seriousness of southern African food shortages in 2002 and 2003, an audit has said.
Many Zimbabweans still require food aid
Auditors Valid International said some fund-raising campaigns had talked of famine or a crisis of biblical proportions, which was an exaggeration.
The audit said this approach could lessen credibility in future appeals.
A spokesman for the charities said most of the report had been positive, but they would learn from any mistakes.
The charities raised $29m, and the report says their work saved lives and eased suffering.
As well as using misleading or emotive language, the audit said some groups had not consulted local people enough and did not fully understand their needs.
For example, one charity provided an expensive diesel pump to irrigate a small field where a foot pump would have been sufficient.
And the report said there was not enough understanding of how the Aids epidemic affects the ability to cope with food shortages.
Richard Miller, a spokesperson for the charities' umbrella Disasters Emergency Committee, said the charities would in future pay more attention to whether people wanted money rather than food and what kind of seeds are usually grown in each area.
The BBC's Stephanie Irvine says the report does not question the validity of charities running campaigns for disaster prevention, but rather suggests ways in which those campaigns could work more effectively.