A Black Box warning is the highest safety-related warning that medications can have assigned by the Food and Drug Administration. 

FDA Warning: serious adverse reactions including tendinitis, tendon rupture, peripheral neuropathy, central nervous system damage,  mental health issues, serious low blood sugar, risk of ruptures or tears in the aorta  and exacerbation of myasthenia gravis

FDA Levaquin Label 06/28/2019

https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/020634s069lbl.pdf#page=51

FDA Cipro Label 05/03/2019

https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/019537s089,020780s046lbl.pdf#page=38

FDA Avelox 05/03/2019

https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/021085s065,021277s061lbl.pdf#page=33

FDA Press Release 2016:

https://www.fda.gov/news-events/press-announcements/fda-updates-warnings-Fluoroquinolone-antibiotics

Label Changes 2013:

Risk for possible permanent nerve damage

https://wayback.archive-it.org/7993/20170112031629/http:/www.fda.gov/Drugs/DrugSafety/ucm365050.htm

FDA Black Box Warning added in 2008:

Fluoroquinolones are associated with an increased risk of tendinitis and tendon rupture

https://wayback.archive-it.org/7993/20170112032310/http:/www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm126085.htm

Multiple FDA Warnings & Articles:

https://www.fda.gov/search?s=+Fluoroquinolone&sort_bef_combine=rel_DESC

FQAD (Fluoroquinolone Associated Disability):

In  2015, after victim testimonies before the Antimicrobial Drugs Advisory  Committee and the Drug Safety and Risk Management Advisory Committee of  the FDA, a cluster of recognized symptoms became known as FQAD  (Fluoroquinolone Associated Disability).  The CDC has yet to recognize FQAD.   Please note these symptoms do not include many of the severe common adverse effects continually reported in support groups by thousands living with this toxicity and yet to be fully acknowledged  by any government entity.