Applies to codeine: compounding powder, injectable solution, oral solution, oral tablet General The most frequently observed adverse reactions include drowsiness lightheadedness, dizziness, sedation, shortness of breath, nausea, vomiting, sweating, and constipation. This article briefly discusses the true opioid allergy versus pseudoallergy, opioid side effects, and alternative options to control pain. Allergy Symptoms All opioids, particularly the naturally occurring and semisynthetic compounds, cause allergic reactions. Serious adverse reactions associated with codeine are respiratory depression and, to a lesser degree, circulatory depression, respiratory arrest, shock, and cardiac arrest. The most frequently observed adverse reactions with codeine administration include drowsiness, lightheadedness , dizziness, sedation, shortness of breath, nausea, vomiting, sweating, and constipation. Some medicines can interact with codeine and cause a serious condition called serotonin syndrome. Be sure your doctor knows if you also take stimulant medicine, herbal products , or medicine for depression , mental illness, Parkinson's disease , migraine headaches, serious infections, or prevention of nausea and vomiting. More serious signs of an allergic reaction to codeine may include heart palpitations, extreme dizziness, or changes in blood pressure. In some cases, the patient may become disoriented or go into shock. Typically, a codeine allergy will not occur with the initial or first exposure of the drug but will most often take place with a subsequent exposure. Often times, codeine allergies are somewhat genetic in scope meaning that if your parents or grandparents are allergic to codeine, you are likely to be allergic to the drug as well. Having a codeine allergy is a problem some people face, which makes them unable to take this prescription opioid for pain or to treat a cough. codeine allergy, not unheard of, not TERRIBLY serious, means you probably should avoid it e future. An anti-allergy med like Benedryl should help Find information about common, infrequent and rare side effects of Codeine Sulfate Oral. Codeine is an opiate used to treat pain, as a cough medicine, and for diarrhea. It is typically used to treat mild to moderate degrees of pain. Serious side effects may include breathing difficulties and addiction. It is unclear if its use in pregnancy is safe.