Methadone detoxification can be a very uncomfortable and challenging experience. Withdrawal Symptoms usually begin between twenty-four and forty-eight hours after the user's last dose of the drug. Common symptoms include: stomach cramps, sweating, nausea, extreme cravings, tremors, irritability, sneezing, fever, chills, vomiting, paranoia, fuzzy-headedness, hallucinations and clinical depression. Additionally, these unpleasant methadone withdrawal symptoms will last 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 share that it is important to gradually decrease your dose of the drug over a period of time instead of completely stopping all at once.