Laura Plummer said the prescription pills were for her partner Omar Caboo
Hurghada beach resort.
Laura Plummer, 33, was arrested last month country with 300 tramadol tablets, a painkiller legal in the UK but not in Egypt.
At the hearing -
The shop assistant from Hull said she had "no idea" the painkillers she was carrying were banned in the country.
But local police said that ignorance of the law is no excuse.
Ms Plummer's family hope the judge at her custody hearing will believe she made an innocent mistake, since drug smuggling can be punishable by death in Egypt.
Tramadol is legal in the UK with a prescription but banned in Egypt, where many are addicted to the opiate.
In a phone call from her cell, Ms Plummer told the BBC she was given the tablets by a colleague for her Egyptian partner, Omar Caboo, who has "back problems".
She said the colleague put them in a chemist's bag, which she put in her suitcase.
"I did not even look in bag," she said. "I can not tell you how stupid I feel."
Ms Plummer told the BBC her cell in a UK station, but she was having to share it with 25 other women
She added her shared cell was claustrophobic, that it was sometimes hard to breathe and that although her fellow prisoners were trying to look after her, none of them spoke English.
