Psychiatrists' reports said that her personality disorder was so severe that it would be untreatable in hospital.
Christopher Hotton QC, for the prosecution, said that Lloyd dosed her son, Christopher, with almost 125 grammes of salt, which caused him to suffer crippling fits of vomiting, diarrhoea, and terrible stomach cramps.
She began lacing her son's drinks on 19 February last year, giving him up to six doses of salt a day while her husband, Stuart, was at work.
Mr Lloyd, the boy's stepfather, became worried about the boy's health and took him to four different doctors the following week, but none of them diagnosed the problem. The court heard that Christopher was prescribed mild sedatives and even antibiotics after one doctor thought he had tonsillitis.
Nine days after the poisoning began, Christopher was taken to hospital after collapsing at home. He died the following day, 1 March, without regaining consciousness.
Mr Hotton said: "Salt poisoning is far from unknown but the age of the child in this case is unusual. Mrs Lloyd must have gone to considerable lengths to prevent him getting salt-free liquids and her child must have been in increasing distress."
Lloyd, who was arrested on 5 March, told police that Christopher and his 17-month-old brother, Adrian, had "worn her down". She added: "I never wanted him to die. I just wanted him to feel poorly. The salt made him tired and made him sleep so that I could get some rest."
At an earlier hearing she had admitted manslaughter, on the grounds of diminished responsibility and cruelty to a child.
Passing sentence, Mr Justice Potts said: "It is clear you continue to pose a substantial risk to children. Nothing I have heard guarantees that this risk can be avoided. You will not be released while you remain a danger."Reuse content