Opiates may make you sick in the stomach when you first start to take them, and it is guaranteed that they will make you constipated. Respiratory and severe central nervous system depression are often seen at very high doses, and could lead to death in overdose situations. Opiods are available in a wide range of dosage forms. They may be given as shots into the muscle or fat, under the tongue, or put into a vein or around the spinal cord. Some are available in a nasal spray that is absorbed through the nasal passages.
Oral administration is the most common route via capsule, tablet, or solution.
It may also be of value for those who cannot tolerate or swallow oral preparations. Opiods have a long history of being safe for short term use during pregnancy. The best tolerated opiods that have the least amount of side effects include morphine, Dilaudid, fentanyl, methadone, oxycodone, and hydrocodone. Despite the fact that opiods have been shown to be safe, their long term use during pregnancy has not been recommended. References Clark, J. B. F., Queener, S. F., et al.