Lupus has long been a complicated disease, affecting the joints in some people and the heart and other organs in others. With no clear treatment, managing lupus has meant managing each patient's own symptoms. But now, for the first time in almost 50 years, Canadians with lupus have a new treatment option.

Health Canada has just approved a drug called Benlysta (belimumab) specifically for the treatment of systemic lupus erythematosus (SLE), the full name of lupus. It's expected to become available to patients in Canada in September.

Lupus specialist Dr. Murray Urowitz explains that lupus is an autoimmune disease.

"In a lupus patient, their immune system, which is supposed to protect them, actually turns against them so that the body starts making antibodies against its own tissue," he explained to CTV's Canada AM Tuesday.

Those antibodies then cause severe inflammation, which is the body's normal response to injury or infection.

"The inflammation, which can be compared to a little fire, breaks out in different parts of the body. So if the fire breaks out in the skin, you get a rash. If it breaks out in the joints, you get arthritis, if it breaks out in your kidneys, you get nephritis," he says.

No one knows what sparks the condition, which affects nine times more women than men.

Rowena Rodriguez was 19 years old when she was diagnosed. At first, doctors couldn't understand why she suddenly lost 30 pounds and a large portion of her hair. She was finally diagnosed in hospital.

For the last 12 years, she has woken up every morning not knowing what symptoms she'll have.

"One of the challenges is you don't really know what the next day will bring," Rodriguez told Canada AM. "Some days I fell like I can run a marathon and have tons of energy, and then other days, I wake up and struggle to get out of bed. Some days I wake up with fevers, headaches, I can't be out in the sun – you just never know."

Urowitz says in lupus, the immune system produces "attack proteins" but it's been unclear how to readjust the immune system to stop these proteins. The last drug approved for lupus was in 1958, and it is no longer used.

The usual treatments today include corticosteroids, other anti-inflammatory drugs and antimalarial medications. Immunosuppressive drugs are also sometimes used, but they can carry side effects.

"Until now, in order to readjust the immune system, we blasted the whole immune system, hoping to get rid of the bad parts. But we also got rid of some of the good parts."

Benlysta is a targeted therapy, he says.

"This aims at one particular protein which nourishes the cells that produce those antibodies," says Urowitz.

Benlysta targets a protein called BLyS, or B-lymphocyte stimulator), which helps antibodies called B cells to survive. Benlysta is a monoclonal antibody therapy that's given intravenously. The drug inhibits the activity of BLyS, which then inhibits the survival of autoreactive B cells.

The drug is not without some controversy. Last year, a committee of the Food and Drug Administration in the U.S. endorsed the drug by a 13-to-2 vote, despite reservations from some on the committee who said the drug was only marginally effective.

According to data from the clinical trials of the drug, about 11 patients must be treated for one to benefit. But the committee decided that there was a need for a lupus drug with even mild efficacy.

As well, African-Americans, who have a higher incidence of the disease, did not seem to respond well to the drug, although too few of them participated in the studies to be sure. More studies are planned in those of African descent.

The drug, developed by Human Genome Sciences and marketed jointly with GlaxoSmithKline, can also cause nausea, diarrhea, fever, depression, and other side effects.