Urticaria and angioedema: molecular mechanisms & dependencies

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

Human evidence only

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What acts on it

Of 237 challenges with various non-steroidal anti-inflammatory drugs and paracetamol in 101 intolerant patients, 19 challenges were positive and 2 patients developed anaphylactic shock, with a ratio of positive to total challenges of 7 of 83 for paracetamol, 2 of 49 for imidazole-hydroxybenzoate and 0 of 30 for nimesulide, and the authors conclude that a positive history of intolerance to a given drug is sufficient reason to contraindicate its use even for diagnostic challenge, which should be restricted to assessing tolerability of alternatives.
Paracetamol → Urticaria and angioedema source_derived_draftungraded
Experimental context and source evidence
evidence_span
{"source_cache": "artifacts/paracetamol-research/7506185.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "b38b08631ecb8137b8297b631b8dab0a4378d5445e29c557e3586b546e0e874f", "start_char": 0, "end_char": 1590, "text_sha256": "b38b08631ecb8137b8297b631b8dab0a4378d5445e29c557e3586b546e0e874f"}
experimental_model
Oral challenge series in 112 and then 284 patients intolerant of non-steroidal anti-inflammatory drugs
exposure
Challenges with aspirin, dipyrone, paracetamol, imidazole-hydroxybenzoate and nimesulide
limitations
Provides the denominator that the case reports lack, and records two anaphylactic shocks during challenge, which is why the authors restrict the procedure.
nutrient_topic
Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
organism
Human
plain_language
About one in twelve challenges with paracetamol was positive in people already intolerant of these drugs.
primary_references
[apap-p7506185] Oral challenge with alternative nonsteroidal antiinflammatory drugs (NSAIDs) and paracetamol in patients intolerant to these agents. (1993). https://pubmed.ncbi.nlm.nih.gov/7506185/ DOI: 10.2165/00003495-199300461-00065
tissue_or_cell_type
Whole body
Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 480–491
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Oral challenge series in 112 and then 284 patients intolerant of non-steroidal anti-inflammatory drugs · source_derived_draft · unverified_draft
### apap-seven-in-eighty-three Of 237 challenges with various non-steroidal anti-inflammatory drugs and paracetamol in 101 intolerant patients, 19 challenges were positive and 2 patients developed anaphylactic shock, with a ratio of positive to total challenges of 7 of 83 for paracetamol, 2 of 49 for imidazole-hydroxybenzoate and 0 of 30 for nimesulide, and the authors conclude that a positive history of intolerance to a given drug is sufficient reason to contraindicate its use even for diagnostic challenge, which should be restricted to assessing tolerability of alternatives. Condition category: normal nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: About one in twelve challenges with paracetamol was positive in people already intolerant of these drugs. organism: Human tissue_or_cell_type: Whole body experimental_model: Oral challenge series in 112 and then 284 patients intolerant of non-steroidal anti-inflammatory drugs limitations: Provides the denominator that the case reports lack, and records two anaphylactic shocks during challenge, which is why the authors restrict the procedure. exposure: Challenges with aspirin, dipyrone, paracetamol, imidazole-hydroxybenzoate and nimesulide evidence_span: {"source_cache": "artifacts/paracetamol-research/7506185.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "b38b08631ecb8137b8297b631b8dab0a4378d5445e29c557e3586b546e0e874f", "start_char": 0, "end_char": 1590, "text_sha256": "b38b08631ecb8137b8297b631b8dab0a4378d5445e29c557e3586b546e0e874f"} [apap-p7506185] Oral challenge with alternative nonsteroidal antiinflammatory drugs (NSAIDs) and paracetamol in patients intolerant to these agents. (1993). https://pubmed.ncbi.nlm.nih.gov/7506185/ DOI: 10.2165/00003495-199300461-00065
Complete structured claim and evidence
Of 256 patients with a history of recent pseudoallergic skin reactions caused by non-steroidal anti-inflammatory drugs who underwent elective oral challenges, 48 or 19% reacted to acetaminophen or nimesulide, with similar proportions among those with chronic urticaria at 23% and otherwise normal subjects with a history of aspirin-induced urticaria at 19% while pyrazolone-intolerant patients showed the lowest number at 4%, aspirin intolerance was a risk factor for acetaminophen or nimesulide induced urticaria with a relative risk of 5.4, a history of anaphylactoid reactions carried a relative risk of 5.7, and atopy raised reactivity to nimesulide from 9 to 23%.
Paracetamol → Urticaria and angioedema source_derived_draftungraded
Experimental context and source evidence
availability_state
biomarker_context Imported condition classification; unverified.
evidence_span
{"source_cache": "artifacts/paracetamol-research/10400483.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "7ea713edb6955db38992c5372794d93c0d52f841d3f8897817286f7f66d28605", "start_char": 0, "end_char": 2662, "text_sha256": "7ea713edb6955db38992c5372794d93c0d52f841d3f8897817286f7f66d28605"}
experimental_model
Elective oral challenges in 256 patients with a history of pseudoallergic skin reactions to non-steroidal anti-inflammatory drugs
exposure
Increasing doses of acetaminophen and nimesulide across three patient groups
limitations
A large challenge series that puts a rate on the cross-reactivity and identifies risk factors. Patients were selected for a history of reacting, so the rates apply to that population and not to the general one.
nutrient_topic
Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. · Paracetamol
organism
Human
plain_language
One patient in five who reacts to aspirin also reacts to paracetamol, so it is not automatically the safe substitute.
primary_references
[apap-p10400483] Risk factors for acetaminophen and nimesulide intolerance in patients with NSAID-induced skin disorders. (1999). https://pubmed.ncbi.nlm.nih.gov/10400483/ DOI: 10.1016/s1081-1206(10)63166-3
tissue_or_cell_type
Skin
trigger_kind
biomarker_context Imported condition classification; unverified.
Paracetamol: the enzyme it reduces rather than blocks, the isoform that turned out not to exist, the metabolite that carries the analgesia, and the metabolite that destroys the liver (2026-09-22) · lines 467–478
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Elective oral challenges in 256 patients with a history of pseudoallergic skin reactions to non-steroidal anti-inflammatory drugs · source_derived_draft · unverified_draft
### apap-twenty-percent-cross-react Of 256 patients with a history of recent pseudoallergic skin reactions caused by non-steroidal anti-inflammatory drugs who underwent elective oral challenges, 48 or 19% reacted to acetaminophen or nimesulide, with similar proportions among those with chronic urticaria at 23% and otherwise normal subjects with a history of aspirin-induced urticaria at 19% while pyrazolone-intolerant patients showed the lowest number at 4%, aspirin intolerance was a risk factor for acetaminophen or nimesulide induced urticaria with a relative risk of 5.4, a history of anaphylactoid reactions carried a relative risk of 5.7, and atopy raised reactivity to nimesulide from 9 to 23%. Condition category: biomarker_context nutrient_topic: Paracetamol research collection; topical membership is not evidence of a direct clinical effect, and the drug is recorded separately from the metabolites NAPQI and AM404. plain_language: One patient in five who reacts to aspirin also reacts to paracetamol, so it is not automatically the safe substitute. organism: Human tissue_or_cell_type: Skin experimental_model: Elective oral challenges in 256 patients with a history of pseudoallergic skin reactions to non-steroidal anti-inflammatory drugs limitations: A large challenge series that puts a rate on the cross-reactivity and identifies risk factors. Patients were selected for a history of reacting, so the rates apply to that population and not to the general one. exposure: Increasing doses of acetaminophen and nimesulide across three patient groups evidence_span: {"source_cache": "artifacts/paracetamol-research/10400483.abstract.txt", "locator": "Indexed abstract; zero-based, end-exclusive Unicode character offsets", "file_sha256": "7ea713edb6955db38992c5372794d93c0d52f841d3f8897817286f7f66d28605", "start_char": 0, "end_char": 2662, "text_sha256": "7ea713edb6955db38992c5372794d93c0d52f841d3f8897817286f7f66d28605"} [apap-p10400483] Risk factors for acetaminophen and nimesulide intolerance in patients with NSAID-induced skin disorders. (1999). https://pubmed.ncbi.nlm.nih.gov/10400483/ DOI: 10.1016/s1081-1206(10)63166-3
Complete structured claim and evidence

The events it takes part in

A mechanism often involves more than two components. These are the full events, with every participant and its role.

Situations it appears in

Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

Open hypotheses

Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.

This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

Urticaria and angioedema