She had three operations last year, including the removal of her large bowel.
She missed more than six months schooling at Cromwell College and did not achieve NCEA level 3 because of the upheaval.
The 18-year-old is enrolled in the pre-nursing course at Otago Polytechnic.
Now adjusting to student life, she was trying new medication in the hope it would enable her to remain without an ileostomy bag, which she needed for a time last year.
Saturday is World IBD Day, highlighting Crohn's disease, ulcerative colitis and indeterminate colitis.
With about 15,000 sufferers, New Zealand had a high rate of irritable bowel disease.
While there were theories about diet and upbringing, the cause of its high prevalence was unknown.
The sooner IBD was diagnosed the better, as sufferers were less likely to have complications such as a perforated bowel, which would require invasive surgery.
Once she has trained as a nurse, Miss Smith wanted to specialise in gastroenterology, with a particular interest in paediatrics, in order to help other IBD sufferers.
Peak onset for IBD was 15 to 35, with Miss Smith noticing her first symptoms about the age of 14.
She tried to "keep them quiet" - symptoms of sharp pain, blood in her stool and vomiting.
Losing 10kg was a catalyst to seek medical attention, and a diagnosis followed.
Weight loss was a key feature of IBD, necessitating steroids and "horrible" protein drinks.
Miss Smith said she enjoyed good support from most friends, with the problem harder to talk about with some people than others.
For some, her illness was "gross", as it involved the bowel.
People often confused IBD with irritable bowel syndrome, which was much less serious but was sometimes a symptom of the former, she said.
IBD was more common than people realised, and she had been surprised by how many fellow sufferers she had met since moving to Dunedin this year.
Yesterday, at Parliament, Crohn's and Colitis New Zealand (CCNZ) launched a survey of New Zealand IBD sufferers to measure the impacts of the diseases.
When carried out in Europe, the survey found 64% of IBD sufferers required emergency-level care before their diagnosis.
"The results of the European survey underscores the severity of IBD and highlights the burden these diseases place not just on the people living with them, but also the impact on health services, relationships, and daily life,"
Wellington Hospital gastroenterologist Dr John Wyeth said in a press release.
The survey was available to IBD sufferers through CCNZ's website.
