In some patients, this medication may cause serious side effects that will require immediate medical attention. These adverse reactions are as follow: persistent nausea, changes in the amount of urination, pronounced restlessness, seizures, or coughing up blood or vomit that looks like coffee grounds. Other side effects that are not as dangerous can include weight loss, dizziness, tremors, loss of appetite, insomnia, restlessness, or mild nausea.