"I am not the only one doing this," she said. "I am 76 years old and I have cousins in the same age group who are all doing it.
"They are actually going into hospitals and massaging people who are in pain and the doctors are turning a blind eye."
MPs on the committee also turned a blind eye to that extraordinary revelation, instead focusing on how effective the cream was.
Labour MP Liz Craig asked whether Mullen needed to supplement it with another conventional medicine.
"No … If you've got arthritis is really is a boon," Mullen said.
"Half my family are using the cream. We all get rheumatoid arthritis, and they use my cream. They don't take painkillers either."
Did it just take the edge off or did it completely relieve her symptoms?
"If you rub it onto your skin, it goes straight into your bloodstream, within 20 minutes you're comfortable and it will last for about four hours," she said.
Mullen echoed the comments of many submitters in saying she wanted to be able to medicate herself with cannabis legally. She wants to grow a plant or two for personal use without fear of prosecution.
Although the law change will create a legal exemption for terminally-ill patients, they will initially only have access to approved cannabis products, which are relatively expensive.
"I really don't want to go to jail for doing this," Mullen said. "But I am going to continue doing it. It is a medicine to me."
Victoria Catherwood, a medical student from Christchurch, also told the committee today that she would not qualify to use medical cannabis legally after the law change.
She has a brain tumour, which initially gave her "crippling" double vision, led to vomiting, and caused her to slur her words.
When she was first diagnosed, Catherwood was given a 40 per cent chance of still living in five years. That does not meet the threshold for accessing medical cannabis under the proposed regime.
"This is my story and this is my struggle," she told the MPs. "My medical treatment is currently being withheld from me."
Catherwood said she also cared for her mother, who has terminal breast cancer which has spread to her lungs, liver and bones.
"I have lived with her for three years and I have witnessed huge benefits from her pain, nausea, vomiting, appetite … from using cannabis as a medicine [rather] than conventional drugs."
Former Green MP Nandor Tansczos, who has lobbied for cannabis law reform for 30 years, said the legislation would help New Zealand to catch up with the rest of the world.
However, he said that without significant changes it would create the "most impractical and unhelpful regime on the planet".
It should be up to doctors, not MPs, to decide whether cannabis was appropriate for a patient, he said. He wanted the legal exemption to be much broader and apply to a list of qualifying conditions, not just terminal cases.
Health Minister David Clark has previously said that the Government wanted the scope of the exemption to be narrow, because it was only meant to be a compassionate measure until a full medical cannabis regime was established - expected to take about two years.
Many submitters have admitted to breaking the law at the hearings, but did not appear to be put off by a warning from Parliament last week that their submissions would be made public.
While some appearing at Parliament today were listed as "anonymous", most were happy to publicly reveal their use of cannabis.
