True Opioid allergy vs. Pseudoallergy vs. Adverse effects
Like any other drugs, opioids can produce many allergic reactions and side effects. The allergies associated with opioids are of two main types i.e., true opioid allergy and pseudoallergy. Although both types present with similar symptoms, there’s a marked difference in the cascade of these allergies. Let’s briefly discuss both of these types along with the general adverse effects of opioids.
True Opioid allergy
Allergies are the response of our immune system to foreign substances to which it becomes hypersensitive. In true opioid allergy, opioids release the special chemical known as “histamine” in the body. Histamine produces many allergic effects such as hypotension, urticaria, and tachycardia. However, previous exposure to opioid is required for true opioid allergy.
Other symptoms that may appear in results of allergy are:
Hypotension which is severe.
Meperidine, Codeine, and Morphine mostly cause allergic reactions.
True allergy to opioids is less.
Pseudoallergies are allergic reactions that are also caused by the histamine release. These allergies can initiate even from the first dose of opioids and doesn’t require prior sensitization (unlike to true opioid allergy).
Symptoms of this type of allergy may involve itching, sweating, and flushing. Some symptoms associated with true allergy also appear in pseudoallergies, such as elevated heart rate, hives, and low blood pressure. Other common symptoms include angioedema, gastrointestinal symptoms, skin flushing, edema, headache, and shock.
Adverse effects of opioids:
Adverse effects of opioids mainly occur due to the direct binding of opioids to body cells and the release of histamine. These reactions are usually dose-dependent. Common adverse effects related to opioid includes the following:
- Dry mouth
- Deficiency of androgens in the body
- Retention of urination
- And the severe complications such as respiratory depression and addiction.
How common is an opioid allergy?
The incidence of true allergy to opioids is rare. There is a less than 2% incidence of true allergies in response to opioids. However, there is a relatively higher incidence of pseudo allergies associated with opioids.
Symptoms of opioid allergy
The symptoms of true opioid allergy include the following,
- Severe hypotension
- Maculopapular rash
- Pustular rash
- Erythema multiforme
- Allergic dermatitis or eczema
The early symptoms include flushing, nasal congestion, hypotension, pruritus, bronchospasm, urinary emergency, diarrhea, vomiting, and death. In addition, anaphylactic reactions can occur in opioid allergy. Anaphylactic reactions are sometimes so severe that they can lead to shock and coma.