You may experience only a few, some, or all of the effects listed below. You may experience them mildly or strongly.

There are some effects of methadone which are understood:

1. Its action on the brain can cause:

· A high/mood change that is less intense but longer lasting than heroin

· Controlling/levelling of emotions

· Drowsiness / sleep

· Feeling or, rarely, being sick. If you are sick after taking methadone it is more likely to be caused by a medical problem (or, if you drink, by alcohol) than by methadone - get your doctor to check it out

· Slower, shallower breathing (which is dangerous in overdose)

· Reduced cough reflex

· Reduction of physical pain.

2. its action on the nerves that control many involuntary functions in almost all cases causes:

· Small pupils

· Constipation

and can cause:

· Dryness of the eyes, nose and mouth

· Reduced blood pressure

· Difficulty in passing urine.

3. Methadone may cause the release of histamine (which is normally only released in allergic reactions) by rupturing the cells that produce histamine. This is not an allergic reaction. It causes:

· Sweating

· Itching

· Flushing of the skin

· Narrowing of the air passages in the lungs.

Methadone has also been said to cause effects which are not understood and may or may not be caused by being on methadone:

Reduced or absent menstrual periods - this is more likely to be caused by stress or poor diet than opiates: it is possible to get pregnant even if you are riot having periods

Reduced sexual desire - in men this may be due to reduced testosterone levels

Reduced energy

A heavy feeling in your arms and legs.

But (unless it has made you drowsy) it won't affect:

Coordination

Speech

Touch

Vision

Hearing.