Kymberley Holden, 27, of Codnor in Derbyshire, died in November 2014 from high levels of OxyNorm.
She had been prescribed ten times the correct dosage by Dr Lawrence Axten, who has apologised for his error.
Dr Axten told her inquest he unwittingly gave her a concentrated dose of the medication.
Ms Holden was prescribed OxyNorm to help her deal with severe pain in her right leg and took three doses in the hours leading up to her death.
Tests showed she died from oxycodone intoxication - the generic name for OxyNorm - and Devic's disease.
Lalitha Vaithianathar, her consultant neurologist and a forensic toxicologist, told Nottingham Coroner's Court it was the dosing of liquid OxyNorm over a short period of time in the final hours that caused the respiratory depression that led to her death.
Coroner Elizabeth Didcock said the prescription error did not cause the 27-year-old's death, but made a "significant contribution".
She added she "did not have confidence that the GP practice understands fully the duty to report serious incidents nor the duties to co-operate with a coronial investigation".
Ms Holden's father Stephen said after the inquest: "I found the conclusion was satisfactory and as good a conclusion as she could come to.
"I understand ... there are more policies and procedures and changes to come to hopefully prevent this from happening to anybody else.
"It has been a very long, very difficult and very trying time."
Ian Dye, her boyfriend, said: "She was the love of my life
"I hope the coroner's recommendations are followed. There was a lack of knowledge about certain controlled drugs and I hope that will improve in the future and prevent something like this happening again."
The family said a civil case was being considered.
A prescription error "significantly contributed" to the death of a woman who was diagnosed with multiple sclerosis, a coroner has ruled.