Hi, Zyrtec (cetirizine) and Flonase (fluticasone) are commonly used medications for the treatment of allergies. While they are generally considered safe, they may cause side effects in some individuals. One potential side effect of Zyrtec and Flonase is liver damage. Elevated levels of ALT and AST are indicators of liver damage, but they can also be caused by other factors such as alcohol use, obesity, viral hepatitis, and certain medications. In some cases, Zyrtec and Flonase have been associated with liver damage. However, the incidence of liver damage caused by these medications is very low. It is important to note that liver damage from Zyrtec and Flonase is rare and usually occurs in individuals with preexisting liver conditions or who are taking high doses of these medications for an extended period. It is possible that the allergy shots you started in December could also be contributing to the elevated ALT and AST levels, although this is less likely than medication-induced liver damage. If you are concerned about your liver function tests, it is important to discuss them with your healthcare provider. They can help determine the cause of the elevated levels and decide whether any changes to your medication regimen are necessary. In some cases, additional testing may be needed to further evaluate liver function. If you require a personalized response, kindly use the Ask A Doctor service and post a follow-up. Take care. Hope I have answered your question. Regards, Dr. Priyanka, General & Family Physician