Adverse effects
Adverse effects of methadone include:
Sedation
Constipation
Flushing
Perspiration
Heat intolerance
Dizziness or fainting
Weakness
Chronic fatigue, sleepiness and exhaustion
Sleep problems such as drowsiness,
Insomnia
Constricted pupils
Dry mouth
Nausea and vomiting
Low blood pressure
Headache
Heart problems such as chest pain or fast/pounding heartbeat
Abnormal heart rhythms
Respiratory problems such as trouble breathing, slow or shallow breathing (hypoventilation), light-headedness, or fainting
weight gain
Memory loss
Itching
Difficulty urinating
Swelling of the hands, arms, feet, and legs
Mood changes, euphoria, disorientation
Blurred vision
Decreased libido, difficulty in reaching orgasm, or impotence
Missed menstrual periods,
Skin rash
Central sleep apnea

Withdrawal symptoms
Physical symptoms

Lightheadedness
Tearing of the eyes
Mydriasis (dilated pupils)
Photophobia (sensitivity to light)
Hyperventilation syndrome (breathing that is too fast/deep)
Runny nose
Yawning
Sneezing
Nausea, vomiting, and diarrhea
Fever
Sweating
Chills
Tremors
Akathisia (restlessness)
Tachycardia (fast heartbeat)
Aches and pains, often in the joints or legs
Elevated pain sensitivity
Blood pressure that is too high (hypertension, may cause a stroke)Cognitive symptoms

Suicidal ideation
Susceptibility to cravings
Depression
Spontaneous orgasm
Prolonged insomnia
Delirium
Auditory hallucinations
Visual hallucinations
Increased perception of odors (olfaction), real or imagined
Marked increase in sex drive
Agitation
Anxiety
Panic disorder
Nervousness
Paranoia
Delusions
Apathy
Anorexia (symptom)Methadone withdrawal symptoms are reported as being significantly more protracted than withdrawal from opioids with shorter half-lives. When used for opioid maintenance therapy, Methadone is generally administered as an oral liquid. Methadone has been implicated in contributing to significant tooth decay. Methadone causes dry mouth, reducing the protective role of saliva in preventing decay. Other putative mechanisms of methadone-related tooth decay include craving for carbohydrates related to opioids, poor dental care, and general decrease in personal hygiene. These factors, combined with sedation, have been linked to the causation of extensive dental damage.
However, it does represent the initial trajectory of attack of an amine on a carbonyl group and was an important piece of experimental evidence for the proposal of the Bürgi–Dunitz angle for carbonyl addition reactions. History
Methadone was developed in 1937 in Germany by scientists working for I.G. Farbenindustrie AG at the Farbwerke Hoechst who were looking for a synthetic opioid that could be created with readily available precursors, to solve Germanys opium and morphine shortage problem. On 11 September 1941 Bockmühl and Ehrhart filed an application for a patent for a synthetic substance they called Hoechst 10820 or Polamidon (a name still in regular use in Germany) and whose structure had little relation to morphine or other "true opiates” such as diamorphine (HeroinTM), desomorphine (PermonidTM), nicomorphine (VilanTM), codeine, dihydrocodeine, oxymorphone (OpanaTM), hydromorphone (DilaudidTM), oxycodone (OxyContinTM), hydrocodone (DicodidTM), and other closely related opium alkaloid derivatives and analogues. It was brought to market in 1943 and was widely used by the German army during WWII as a substitute for morphine.In the 1930s, pethidine (meperidine) went into production in Germany; however, production of methadone, then being developed under the designation Hoechst 10820, was not carried forward because of side effects discovered in the early research. After the war, all German patents, trade names and research records were requisitioned and expropriated by the Allies. The records on the research work of the I.G.