Ingestible event markers having high reliability are provided. Aspects of the ingestible event markers include a support, a control circuit, a first electrochemical material, a second electrochemical material and a membrane. In addition, the ingestible event markers may include one or more components that impart high reliability to the ingestible event marker. Further, the ingestible event markers may include an active agent. In some aspects, the active agent, such as a pharmaceutically active agent or a diagnostic agent may be associated with the membrane.