They are believed to have consumed drinks tainted with methanol, which is a cheaper alternative to ethanol but can cause severe poisoning or death.
Ms White was an associate lawyer at a US law film, and was based in London.
Her friend Bethany Clarke, a healthcare worker, also from Orpington, had posted a warning to other travellers on a Facebook group for backpackers in Laos.
“Urgent – please avoid all local spirits,” she wrote. “Our group stayed in Vang Vieng and we drank free shots offered by one of the bars… Six of us who drank from the same place are in hospital currently with methanol poisoning.”
Bianca Jones, 19, from Melbourne, died in hospital on Thursday. Announcing her death on Wednesday, her family said she was “surrounded by love” in her final moments.
Thai authorities said Ms Jones died as a result of brain swelling due to high levels of methanol in her system. Her schoolfriend Holly Bowles, also 19, is said to be in a serious condition and on life support.
She and Ms Bowles had flown from Australia for a “dream getaway” in south-east Asia and were found by staff at the Nana Backpackers Hostel when they failed to leave their room on time.