A 48-year-old woman in Cairns in far north Queensland with serious heart problems has been ordered to serve six months in jail for drug offences committed three years ago.

Karyn Goodier pleaded guilty in the Supreme Court to unlawfully trafficking an unknown quantity of methyl-amphetamines over a six-month period in 2009 and 2010 to support her own drug habit.

Her lawyer had asked for a non-custodial sentence because Goodier's doctor was concerned imprisonment may have grave consequences for her health.

Goodier's lawyer also told the court her client had completed an intensive rehabilitation program with great success in 2011 and had continued to live drug-free.

She was supported in court by a man for whom she has been a carer the past two years.

However, Justice Jim Henry sentenced Goodier to four years in jail, suspended after six months, taking into account her significant health problems.