text: Serum vancomycin levels may be monitored in an effort to reduce side effects. Still, the value of such monitoring has been questioned. Peak and trough levels are usually monitored, and for research purposes, the area under the concentration curve is also sometimes used. Toxicity is best monitored by looking at trough values.
  Immunoassays are commonly used to measure levels of vancomycin.
  Common adverse drug reactions (≥1% of patients) associated with intravenous (IV) vancomycin include:
  * pain, redness, or swelling at the injection site;
  * vancomycin flushing syndrome (VFS), previously known as red man syndrome (or "redman syndrome");
  * thrombophlebitis, which is common when administered through peripheral catheters but not when central venous catheters are used, although central venous catheters are a predisposing factor for upper-extremity deep-vein thrombosis.
  Damage to the kidneys (nephrotoxicity) and to the hearing (ototoxicity) were side effects of the early impure versions of vancomycin, and these were prominent in the clinical trials conducted in the mid-1950s. Later trials using purer forms of vancomycin found nephrotoxicity is an infrequent adverse effect (0.1% to 1% of patients), but this is accentuated in the presence of aminoglycosides.
  Rare adverse effects associated with intravenous (IV) vancomycin (<0.1% of patients) include: anaphylaxis, toxic epidermal necrolysis, erythema multiforme, superinfection, thrombocytopenia, neutropenia, leukopenia, tinnitus, dizziness and/or ototoxicity, and DRESS syndrome.
  Vancomycin can induce platelet-reactive antibodies in the patient, leading to severe thrombocytopenia and bleeding with florid petechial hemorrhages, ecchymoses, and wet purpura.
  Historically, vancomycin has been considered a nephrotoxic and ototoxic drug, based on numerous case reports in the medical literature following initial approval by the FDA in 1958. However, as the use of vancomycin increased with the spread of MRSA beginning in the 1970s, toxicity risks were reassessed. With the removal of impurities present in earlier formulations of the drug, and with the introduction of therapeutic drug monitoring, the risk for severe toxicity has been reduced.