All drugs come with potential side effects such as Stevens Johnson Syndrome, Toxic Epidermal Necrolysis, and others. Quinolone antibiotics are among the drugs linked to a risk of developing this group of drug reactions.

Some drug reactions are comparable to autoimmune diseases. Autoimmune diseases occur when the body’s immune system, which normally defends the body from diseases and illnesses, misfires, and attacks the body’s own tissues. In cases of Stevens Johnson Syndrome, the immune system attacks the skin, the largest organ in the body.

On the milder end of the spectrum sits a disorder called erythema multiforme. A wide variety of drugs can trigger this disorder, including quinolone antibiotics. Erythema multiforme starts with flu-like symptoms, including fever, joint and muscle aches, and a general feeling of malaise. However, these symptoms give way to a painful and itchy rash, with circular “bulls-eye” marks similar to hives all over the body.

The disease comes in two forms: erythema multiforme minor and erythema multiforme major. The minor form is often triggered by viral and fungal infections. However, the major form is most often triggered by reactions to drugs like quinolone antibiotics.

While the exact definition varies, many medical professionals consider the major form of the disorder to be the same disease as Steven Johnson Syndrome, or at least that there is overlap between the worst cases of erythema multiforme and the milder cases of Stevens Johnson Syndrome.

Stevens Johnson Syndrome, or SJS, is a more extreme member of this family of autoimmune reactions that can be triggered by quinolone antibiotics. This group of reactions are a spectrum, with the mildest cases of erythema multiforme on one end, and SJS roughly in the middle.

Like erythema multiforme, SJS symptoms start out with flu-like symptoms. However, the rash is more serious, escalating to blisters, sores and ulcers over most of the body. The damage can also spread to the eyes, mouth, and even the surface of internal organs.

Unlike the milder cases of erythema multiforme, nearly all cases of SJS can be linked to drug exposures like quinolone antibiotics. Mortality rates from SJS range from 5 percent to 30 percent.

However, survivors may face a lifetime of complications, including disabling and disfiguring scarring, blindness, and impaired organ function. However, it is not the most deadly disease in this triad of drug reactions.

Toxic Epidermal Necrolysis, or TEN, forms the deadlier end of the spectrum. Like SJS and erythema multiforme, there is some overlap between TEN and SJS. However, patients with TEN face even more deadly symptoms.

TEN symptoms include patches of skin dying and sloughing off, leaving wounds that closely resemble severe wounds. TEN carries a mortality rate of 40 percent, higher than some strains of the Ebola virus. Like SJS, nearly all cases of TEN can be traced to reactions to drug reactions, including reactions to quinolone antibiotics.