Mental Health  |  OST Drug Issues Pathway - Methadone Side Effects

Mental Health

OST Drug Issues Pathway - Methadone Side Effects

Some of these side effects may be confused with withdrawal symptoms and may be experienced even when the dose is appropriate.

Side effects



Aching muscles and joints

Some individuals report rheumatic type pains and 'bone pain' - uncommon

Medical examination for any underlying pathology. Hot Epsom salts bath may ease symptom

Analgesia and hypo-analgesia

Systemic analgesia, long term can lead to opiate receptor saturation and hypo-analgesia or increased pain sensation

Advise patient to discuss chronic pain with GP/pain specialist


A common side effect

Increase intake of water and fiber and increase exercise. If necessary take regular Lactulose or Movicol


Due to mildly/moderately increased prolactin levels

Check prolactin level and rule out pathology. Seek specialist endocrinologist advice if uncertain

Irregular menstrual cycle/amenorrhoea

Common in women who take opioids

Educate women about the risk of pregnancy despite menstrual irregularity/amenorrhoea

Lowered sex drive and impotence

Common with all opioid use

Reduce dose but needs to be weighed against compromising outcomes on MMT


Fluid retention, puffiness, swelling, particularly of feet & ankles - uncommon

Usually resolves within a few weeks of starting treatment

Other G.I effects


Nausea and vomiting

Reduced gastric emptying

Elevated pyloric sphincter tone

Biliary tract outflow effects (can result in biliary spasm)

Loss or increased appetite

To reduce nausea and vomiting, suggest patient eat before consuming dose and drink dose slowly

Other symptoms may be reduced by reducing the dose


Increased Perspiration

Common especially at peak serum levels


Q-T prolonging effect

Potential for QTc prolongation, especially if combined with other drugs with similar effect

Annual ECG tests recommended. See medications also with QT prolonging effects


Drowsiness may be experience at peak serum level (3 to 4 hours after dose) especially during

initial stabilisation

Check serum levels

Reduced dose or split dose may be necessary - see relevant sections

Shallow breathing

From the respiratory depressive action of opioids

Reduce dose

Skin rash/itching


Appropriate skin lotion, e.g. BK lotion or similar emollient, antihistamine

Tooth decay/dry mouth

Opioids reduce the production of saliva


Increase fluid intake

Chew sugar free gum

Regular flossing and tooth brushing

Regular dental checks

Weight gain

Occurs in small number of patients

Assistance with weight management strategies

Weight loss

Lack of appetite, may be associated with mood

Assistance with weight management strategies

*See Section 6.2 Managing Side Effects page 44 and Appendix 4 Side Effects page 101 of
 " New Zealand Practice Guidelines for Opioid Substitution Treatment 2014"

Last updated : Thursday, January 09, 2020
Next review date : Friday, January 08,2021

Disclaimer: This site is intended to be flexible and frequently updated. While every effort has been made to ensure accuracy, all information should be verified.