According to the new version of the code, which will take effect July 1, 2016, imprisonment will also come with fines of up to VND100 million (US$4,460) for such offenses.
Currently violators are only be asked to pay fines of up to VND20 million. Vietnam has been seeking stronger measures to control the rampant use of illegal substances and abuse of antibiotics in farming.
Nguyen Van Viet, chief inspector of the Ministry of Agriculture and Rural Development, said in particular the use of salbutamol in pigs persists, especially in southern provinces.
Many farms have been caught using salbutamol, a drug used to treat asthma and lung conditions under strict supervision, to enhance leanness in pork.
Consuming salbutamol residues can cause a rapid heart rate, dizziness, headache and anxiety in humans, especially in those with heart diseases and hypertension.
Viet said his agency found 98 of 1,000 samples containing salbutamol during an inspection in January. The rate reduced in a subsequent inspection in March, with only three positive cases among 576 samples tested.
However, he is still concerned that the banned substance will be widely used again without strong measures.
The agricultural ministry will coordinate with the Ministry of Public Security to launch more inspections this month, he said.
Official data showed that 20 companies imported a total of 9.14 tons of salbutamol into Vietnam last year, only 10 kg of which were used legally in medicine. That means a very large amount of the drug might have ended up in the animal farming industry.
Local media reported that about three tons are in stock while some six tons have been sold illegally to farmers.
That amount is theoretically enough to be used on six million pigs, or 20 percent of the total hog population in Vietnam.