Methadone detoxification can be a very uncomfortable and challenging experience. Symptoms usually begin between twenty-four and forty-eight hours after the user's last dose of methadone. Common symptoms include: stomach cramps, sweating, nausea, extreme cravings, tremors, irritability, sneezing, fever, chills, vomiting, fuzzy-headedness, paranoia, clinical depression and hallucinations. Additionally, these unpleasant methadone withdrawal symptoms tend to continue much longer than heroin withdrawal symptoms. Depending on the dose of methadone you have been taking the symptoms can last for several weeks to several months. Professionals in the field of methadone detoxification typically advise the gradual decrease of the drug over a period of time instead of completely stopping all at once.