At the Principal Investigator's discretion, participants who were able to achieve the maximum study dose will be invited to continue onto the 2-week treatment course of the study. These participants will return on Days 1 and 2 to the clinic to self-administer the maximum study dose of cockroach extract. After self-administering the maximum study dose, participants will be observed by the clinic nurse for 30 minutes. On Days 3 through 14, participants will take the maximum study dose of cockroach extract daily at home. Participants will be asked to keep a diary and record signs or symptoms experienced after taking each dose.