Parents should be warned that the vaccine may not protect against the disease, and some children may have been exposed at the same time as the index case and go on to develop varicella within a few days, despite immunization. However, the administration of varicella vaccine during the presymptomatic or prodromal stage of the illness is not believed to increase the risk of vaccine-associated adverse effects or more severe natural disease. More than 700 drugs have been implicated in causing diarrhea, with antimicrobials being responsible for about 25 per cent of cases. In clinical practice, two main types of diarrhea are seen. Acute diarrhea usually appears during the first few days of therapy.
Most cases resolve spontaneously after the drug is withdrawn, or with continued drug therapy.
Chronic diarrhea can appear several months or years after the start of long-term treatment, and last for more than three to four weeks. It usually ceases when the drug is stopped. Other cases can be managed by altering the drug dosage. It may be difficult to establish a relationship between a drug and the occurrence of diarrhea, particularly in situations when a long period of time has elapsed between the start of the drug and the onset of symptoms. The diagnosis may rely on excluding other obvious etiologies, and by rapid disappearance of diarrhea upon drug withdrawal, and reappearance of diarrhea upon rechallenge.