The exact symptoms experienced during methadone withdrawal will vary based on individual experience (substance use history, other addictions, length of abuse, etc.). Some of the more common symptoms experienced during methadone detox include: Fatigue and Flu-Like Symptoms Mild to Severe Muscle and Joint Pain Intestinal Distress (Nausea, Vomiting, Diarrhea, Etc.) Headache and Migraine Extreme Fluctuations in Body Temperature. Other effects can include respiratory problems, constipation, accelerated heart rate, hallucinations, depression and anxiety and more. The cruel irony of methadone is that its withdrawal symptoms actually mirror those of heroin withdrawal, the very drug it is meant to treat. Methadone detox requires experienced professional help from a trained clinical professional.