Short-term methadone effects include
Sweating is often increased, especially at night.
Constipation is quite common.
Aching muscles and joints may be experienced. Some people report rheumatism-type aches and pains at various times.
Lowered sex drive is experienced with the use of any opioid, including methadone and heroin.
Skin rashes and itching are experienced by some people.
Sedation (for example, drowsiness, especially soon after a dose).
Fluid retention causing swelling or puffiness of the hands or feet.
Loss of appetite, nausea and vomiting may occur.
Abdominal pain (cramps) may occur.
Tooth decay. Methadone, like all opioids, reduces production of saliva. Saliva contains antibacterial agents which help prevent deterioration of teeth and gums. Poor or irregular diet and inadequate dental care also contribute to tooth decay.
Changes to periods (menstruation) Many women have irregular periods when they use methadone or other opiates