Many adverse effects of licorice poisoning can be seen and most are attributed to the mineralocorticoid effects of GZA. Depending on the dose and intake of licorice, serious problems and even hospitalization can arise. People with previously existing heart or kidney problems may be more susceptible to GZA and licorice poisoning.  It is important to monitor the amount of licorice consumed in order to prevent toxicity. It is difficult to determine a safe level, due to many varying factors from person to person. In the most sensitive individuals, daily intake of about 100 mg GZA can cause problems.  This is equivalent to 50 g licorice sweets. However, in most people, they can consume up to 400 mg before experiencing symptoms, which would be about 200 g licorice sweets. A rule of thumb says a normal healthy person can consume 10 mg GZA a day. 
The consumption of licorice tea also cures many types of cancer with its chemo-preventive effects. Its anti-proliferative effects also restricts the growth of breast cancer cells. Flavonoids like isoliquiritigenin contained in licorice help in the suppression of colon carcinogenesis and activate apoptosis. There are also supporting evidences, which states the anti-tumor action of licorice extracts. These have been found to reduce toxicity stimulated by chemotherapy drugs and check tumor cell production. Yet, patients treated with cisplatin therapy should avoid the use of licorice extract These licorice extracts are also helpful in treating conditions like prostate cancer and prostatitis.
Some other key factors to keep in mind are that you should also have your kidney and liver function checked regularly. Although there are generally minimal concerns with usage of DGL, in regard to your liver and kidney function -- as you would with any other medication you use long-term -- I caution all of my patients to treat supplements like a medication in that they should not be cavalier about using supplements, either. If you are on any supplements or medications on a daily basis, you should always have regular blood work done to monitor your liver and kidney functioning.