This was really helpful i started taking a antibiotics for a wisdom tooth infection and I was wondering if the light spotting was normal or a really bad side effect since I have never experienced this before and i have taken antibiotics before (although it has been a while since i needed any). Since irregular bleeding is on the WARNING part of the meds I was starting to wonder if i should keep taking them (since it is bad to stop in the middle of a round) but i was not having any of the other side effects. This information helped a lot in understanding and calming me down thanks!
A team of researchers at the pharmaceutical company Pliva —Gabrijela Kobrehel, Gorjana Radobolja-Lazarevski, and Zrinka Tamburašev, led by Dr. Slobodan Đokić—discovered azithromycin in 1980. It was patented in 1981. In 1986, Pliva and Pfizer signed a licensing agreement, which gave Pfizer exclusive rights for the sale of azithromycin in Western Europe and the United States. Pliva put its azithromycin on the market in Central and Eastern Europe under the brand name Sumamed in 1988. Pfizer launched azithromycin under Pliva's license in other markets under the brand name Zithromax in 1991. 
Horses with Lyme Disease may benefit from supplements with ingredients that provide general wellness support – such as omega 3 fatty acids , antioxidants, and adaptogens -- as well as support towards specific, affected areas. For example, horses that are displaying joint discomfort may appreciate traditional ingredients like glucosamine, chondroitin sulfate, HA, and MSM . Also look for turmeric, resveratrol, collagen, and various herbs. Muscle recovery can often use an assist from amino acids like lysine, methionine, threonine, and others. Both muscle and neurological systems may find value in the addition of Vitamin E . Also, digestive support from probiotics , prebiotics , and yeast during a course of antibiotics is regularly recommended to help maintain normal, healthy gastrointestinal function, as is reinforcement for gastric (stomach) tissues under stress with ingredients like soothing herbs, soluble (mucilage) fiber, and buffering agents.