Cancer Research UK has received donations of more than £8m in just six days from the #nomakeupselfie trend.
The trend, in which people tweet pictures of themselves without make-up, began generating donations for the charity last week.
By Friday donations to cancer charities through the craze had passed £2m.
But CRUK said today that there had been an unprecedented increase in the volume of donations and visits to its website over the past week, and donations had reached £8m.
"We’ve been overwhelmed by the support people have been showing us through the #nomakeupselfie trend," said Harpal Kumar, chief executive of CRUK. "We don’t receive any government funding for our research, so it’s phenomenal to think that the generosity of the public is enabling us to fund critical research that we didn’t have the money for six days ago.
"It’s been an exciting week, and we’d just like to thank everyone again for their support."
It has also emerged that almost £20,000 donated under the ‘#nomakeupselfie" trend was mistakenly made to Unicef UK instead of CRUK. People texting "Donate" instead of "Beat" had their donations given to the wrong charity.
"Unicef UK believes this error has occurred because of those interested in donating to the #nomakeupselfie campaign sharing the text keyword ‘donate’ – rather than the keyword ‘beat’ – and the text number 70099, which has then been repeated across social media," said Mike Flynn, director of individual giving at Unicef UK.
"‘Donate to 70099’ is an SMS keyword and shortcode combination that Unicef UK has sole use of, specifically for any members of the public who contact us and wish to donate to us via SMS."
Unicef said that £18,625 had so far been identified as being pledged to the charity by accident.
It said it was working with CRUK to redirect the funds to the intended recipient.
"We are now working closely with all parties involved to ensure that this doesn’t happen again," said Flynn.
The conservation charity WWF-UK said that it received about 2,850 texts for information about adopting a polar bear since Friday because people had mistakenly texted the word "bear" rather than "beat".
A spokesman for the charity said it noticed the activity because the campaign was not currently being promoted and usually received about 22 texts a day.
He said the charity did not receive any money from the texts, because it phones people back to set up donations.