Poor liver function
The maximum recommended dose for people with severe liver function impairment is 8 mg/day. In these people, ondansetron is cleared from the body at half to one-third the rate as in healthy people. The concentration of ondansetron in body tissues as opposed to plasma is also higher than in healthy people. Adverse effects
Headache is the most common adverse effect. A review of use for post-operative nausea and vomiting found that for every 36 people treated, one would experience headache, which could be severe.Constipation, diarrhea, and dizziness are other commonly reported side effects. It is broken down by the hepatic cytochrome P450 system and it has little effect on the metabolism of other drugs broken down by this system. Anecdotally, ototoxicity has also been reported if injected too quickly. QT prolongation
Use of ondansetron has been associated with prolongation of the QT interval, which can lead to a potentially fatal heart rhythm known as torsades de pointes. Although this may happen in any person with any formulation, the risk is most salient with the injectable (intravenous) form of the drug and increases with dose. The risk is also higher in people taking other medicines that prolong the QT interval, as well as in people with congenital long QT syndrome, congestive heart failure, and/or bradyarrhythmias. As such, single doses of injectable ondansetron should not exceed 16 mg at one time. (Oral dosing recommendations remain intact, including the recommendation of a single 24-mg oral dose when indicated.) Electrolyte imbalances should be corrected before the use of injectable ondansetron.
Botryomycosis; is a rare chronic granulomatous bacterial infection that affects the skin, and sometimes the viscera. : 255 Botryomycosis has been known to affect humans, horses, cattle, swine, dogs and cats. Presentation
Associated conditions
There are only a handful of documented cases of botryomycosis in humans, and its pathogenesis is not completely understood. However, it is usually described in individuals with impaired immunity, or with an underlying disease such as diabetes mellitus, cystic fibrosis or HIV infection. Causes
Staphylococcus aureus is usually the organism that causes the infection, however it can also be caused by Pseudomonas aeruginosa, Pneumocystis carinii, Proteus spp. and Actinobacillus lignieresii or other species of bacteria. The anatomic structure of its lesion is similar to that of actinomycosis and eumycetoma, and its granules resemble the sulfur granules of actinomycosis. Diagnosis
History
The disease was originally discovered by Otto Bollinger (1843–1909) in 1870, and its name was coined by Sebastiano Rivolta (1832–1893) in 1884. The name refers to its grape-like granules (Gr. botryo = grapes) and the mistakenly implied  fungal etiology (Gr. mykes = fungus). In 1919 the bacterial origin of the infection was discovered. Notes
Concise Review of Veterinary Microbiology - Quinn and Markey 2003

External links
Essay on Pulmonary Botryomycosis