The pain relieving and mind-altering effects of narcotic drugs can be reversed by an injection of another medication called naloxone (or Narcan). This can take effect within seconds (if given via the vein) or minutes (if given via the muscle). Naloxone works by attaching to the nerve receptors and stopping the narcotic drug from doing so. By doing this the pain relief and other effects of the narcotic (such as drowsiness) are abruptly stopped.
The person's body will still take a few hours to break down and excrete the narcotic from their blood system, but they do not feel any effects of the drug. If the naloxone wears off before the narcotic does, the effects of what is left of the narcotic drug can again be felt, unless more naloxone is given. (Out of interest, Naloxone is the same drug given to heroin users who overdose.)
Babies are occasionally given naloxone as an injection if they are severely affected at birth by the narcotic the mother received during the labour. Sometimes the narcotic will suppress the baby's desire to breathe at birth. The naloxone is usually given in combination with the caregiver using a face-mask resuscitator, to artificially ventilate the baby's lungs, until the naloxone works and the baby responds. Your caregiver may also suggest that the baby be placed under observation in the
intensive care nursery for up to 4 to 24 hours, in case the naloxone wears off and the narcotic is still present in high concentrations, suppressing the baby's breathing again.
Some women ask if the naloxone can be given to them just prior to the birth. This is not usually recommended as it would reverse the woman's endorphins abruptly and induce a severe increase in her pain. Naloxone may be given to the woman for medical reasons if the woman is very drowsy and in the very rare circumstance that her own breathing was being slowed.