When a drug is first marketed, it is required that drug makers thoroughly test their products for both safety and efficacy. However, one potential issue stems from the size of these clinical trials.

Though efforts have been made to correct this, at the most, thousands of people typically take the drug as part of the initial testing. While this might sound like a lot of people, often the test subjects do not fully represent the populations that will be taking the drug. Sometimes, this means that serious side effects are not uncovered until a drug reaches the market and millions of patients use it. This may be the case with Zithromax side effects, and could lead to more Zithromax side effect lawsuits.

Zithromax is the American trade name of azithromycin, also sold as the Z-Pak. The drug is extremely effective against a huge range of bacteria, treating everything from strep throat to flesh-eating bacteria. Additionally, the drug is structurally distinct from penicillin. This is important, as many people with penicillin allergies have similar reactions to related drugs, making many common antibiotics risky for them to use. However, since Zithromax does not belong to this family of drugs, people with penicillin allergies can usually use Zithromax safely. However, Zithromax does have some side effects of its own.

One serious Zithromax side effect is dangerous changes in heart rhythm. Other drugs related to Zithromax had demonstrated this side effect, but the Zithromax clinical trials had initially made it appear that this side effect was not seen in Zithromax. However, once the drug hit the market and millions used the drug, the U.S. Food and Drug Administration (FDA) began to observe that patients taking Zithromax had an increased risk of heart problems. It is believed that the drug can alter the rhythm of the heart in such a way that the heart is more likely to seize, causing sudden cardiac arrest. Further studies indicated that this risk is most pronounced in individuals with existing heart conditions. This led to a series of warnings from the FDA and changes to the drug’s labeling over potential Zithromax side effects.

Another serious potential Zithromax side effect is Stevens Johnson Syndrome, or SJS. SJS is an autoimmune reaction, a situation in which the body’s system for fighting infection malfunctions and begins attacking the body’s own tissue. In the case of SJS, the body attacks the skin. This causes a life-threatening rash, which causes blisters, sores, and ulcers on the skin, mouth, and eyes. Serious cases can spread to the internal organs. The disorder can be fatal.

These potential Zithromax side effects are relatively rare, possibly rare enough that these side effects were not initially obvious. However, reports of side effects filed with the FDA once a drug has hit the market have been sufficient for the FDA to issue warnings and update the drug’s labeling.