Please read this first. This guide is a companion to your medical team, not a replacement, and it is
not medical advice.
Everything here is tied to published research. If something you expected is not here, it almost always means we have not mapped a source for it yet,
not that it is unknown to medicine.
acute intermittent porphyria is an early, growing map, so it will look incomplete on purpose: we would rather show less and have every line be something you can check than fill the page with claims we cannot stand behind.
For anything about your own situation, your clinicians hold the full picture.
How this guide is built and why.
What's acute intermittent porphyria?
Acute intermittent porphyria (AIP) is an inherited disorder of heme production. A deficiency of the enzyme hydroxymethylbilane synthase (also called porphobilinogen deaminase, encoded by HMBS) lets toxic heme precursors (ALA and PBG) build up, triggering acute neurovisceral attacks: severe abdominal pain, autonomic upset, neuropathy, and neuropsychiatric symptoms. It is autosomal dominant but has low penetrance, so most gene carriers never have an attack. Attacks are set off by specific drugs, fasting, alcohol, and hormonal changes, so an avoid-list is central to care. This entry confirms HMBS.
| Also indexed as | ORPHA:79276, MONDO:0008294 |
|---|
| Features mapped | 11 |
|---|
| Treatments mapped | 3 |
|---|
| Published sources | 13 |
|---|
| Last reviewed | 2026-08-04 |
|---|
Signs and symptoms
Seizure
Severe attacks can affect the brain and cause seizures, sometimes together with low blood sodium. Several common seizure medicines can worsen porphyria, so drug choice matters.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:42093711, PMID:40186107, ORPHA:79276
Notesplain_language confirmed from PMID:42093711 via curation 2026-06-17. plain_language revised from PMID:42093711 via curation 2026-06-18 [carrie (claude rewrite)]. plain_language confirmed from PMID:40186107 via curation 2026-06-18 [claude (tier3 curation)]. | regrounded primary ORPHA:79276 -> PMID:27982422 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Tachycardia
A fast heart rate (tachycardia) is a common autonomic feature of an acute attack.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesORPHA:79276
Notesplain_language confirmed from PMID:9638723 via curation 2026-06-14. | regrounded primary ORPHA:79276 -> PMID:9638723 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Hypertension
Attacks bring autonomic instability, including high blood pressure (hypertension).
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesORPHA:79276
Notesplain_language confirmed from PMID:9638723 via curation 2026-06-14. | regrounded primary ORPHA:79276 -> PMID:9638723 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Autosomal dominant inheritance
AIP is inherited in an autosomal dominant pattern, but penetrance is low: inheriting the variant gives a predisposition, and most carriers never develop attacks.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:39188285, OMIM:176000
Notesplain_language confirmed from PMID:39188285 via curation 2026-06-14. | regrounded primary OMIM:176000 -> PMID:7866402 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Abdominal pain
The hallmark of an acute attack is severe, poorly localized abdominal pain, often with vomiting and constipation.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesORPHA:79276
Notesplain_language confirmed from PMID:9638723 via curation 2026-06-14. | regrounded primary ORPHA:79276 -> PMID:9638723 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Vomiting
Repeated vomiting, often with severe abdominal pain, is a common feature of an acute porphyria attack.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:39737264, OMIM:176000
Notesplain_language confirmed from PMID:39737264 via curation 2026-06-17. plain_language revised from PMID:39737264 via curation 2026-06-18 [carrie (claude rewrite)]. | regrounded primary OMIM:176000 -> PMID:9638723 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Muscle weakness
Attacks can damage the motor nerves, causing muscle weakness that, if severe, can affect breathing. Weakness can improve when an attack is treated.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:39425488, OMIM:176000
Notesplain_language confirmed from PMID:39425488 via curation 2026-06-18 [claude (tier3 curation)]. | regrounded primary OMIM:176000 -> PMID:36598516 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Hyponatremia
Low blood sodium (hyponatremia) is common in attacks and can itself provoke seizures.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:40186107, ORPHA:79276
Notesplain_language confirmed from PMID:40186107 via curation 2026-06-14. | regrounded primary ORPHA:79276 -> PMID:27982422 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Increased urinary porphobilinogen
Markedly elevated porphobilinogen (PBG) in the urine during an attack is the key diagnostic test.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:9638723, ORPHA:79276
Notesplain_language confirmed from PMID:9638723 via curation 2026-06-14. | regrounded primary ORPHA:79276 -> PMID:23605132 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Motor polyneuropathy
Severe attacks can progress to a motor neuropathy with limb weakness that, untreated, may threaten breathing.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:9638723, ORPHA:79276
Notesplain_language confirmed from PMID:9638723 via curation 2026-06-14. | regrounded primary ORPHA:79276 -> PMID:34375916 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
Peripheral neuropathy
Peripheral neuropathy in acute porphyria can cause pain in the arms and legs and may progress to severe weakness that affects movement.
Evidence ratingweak
Study designontology_import
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:9638723, ORPHA:79276
Notesplain_language confirmed from PMID:9638723 via curation 2026-06-17. plain_language revised from PMID:9638723 via curation 2026-06-18 [carrie (claude rewrite)]. | regrounded primary ORPHA:79276 -> PMID:27982422 on 2026-06-26 [Carrie Schluter, BCPA]
Last reviewed2026-06-26
How it is diagnosed
Acute intermittent porphyria
Diagnosed using: Urinary porphobilinogen (PBG) and ALA.
The source text this rests on
“…elevated urinary porphobilinogen (PBG) and delta-aminolevulinic acid (ALA)…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:39425488 via curation 2026-06-18
Last reviewed2026-06-18
Treatment and management
What the research describes, not a recommendation. Treatment decisions belong with your clinician.
This covers treatments that appear in the published research mapped here. Investigational and experimental therapies are not included, so their absence is a boundary of this map, not a sign they do not exist.
givosiran
Givosiran is an siRNA therapy that silences the ALAS1 enzyme, lowering ALA and PBG; it is given monthly to prevent recurrent attacks.
Used to help with: Acute intermittent porphyria.
The source text this rests on
“Givosiran (siRNA) is an emerging AIP therapy capable of silencing delta-aminolevulinic acid synthase-1…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:39597922 via curation 2026-06-14
Last reviewed2026-06-14
intravenous hemin
Intravenous hemin replenishes the heme pool and is the most effective treatment for a severe acute attack, shutting down the overactive precursor production.
Used to help with: Acute intermittent porphyria.
The source text this rests on
“…intravenous hemin for severe…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:39737264 via curation 2026-06-14
Last reviewed2026-06-14
intravenous glucose loading
Intravenous glucose (carbohydrate loading) is used for milder attacks and supports the body during a crisis by suppressing the pathway that drives precursor build-up.
Used to help with: Acute intermittent porphyria.
The source text this rests on
“…dextrose infusions for mild…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:39737264 via curation 2026-06-14
Last reviewed2026-06-14
Triggers to avoid
In this condition, certain drugs, foods, or other exposures can set off an acute episode in people who are affected, even when they are otherwise well. The research mapped here describes the agents below. This is information, not a recommendation: what to avoid and what is safe for any individual is a conversation for their own care team.
porphyrinogenic drugs
Many common medications can trigger an attack by inducing the ALAS1 enzyme; only drugs confirmed safe in porphyria should be used. Check every new drug against a porphyria-safe list before taking it.
Reported in the research mapped here as able to provoke: Acute intermittent porphyria in people with this condition.
The source text this rests on
“Attacks are often induced by precipitating factors such as drugs, alcohol, infection, fasting or changes in sex-hormone…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:36642627
Notesconfirmed from PMID:9638723 via curation 2026-06-14 | superseded (replace) by PMID:36642627 on 2026-06-19 [carrie]
Last reviewed2026-06-19
fasting
Going without food (fasting, crash dieting, or skipped meals) can trigger an attack; maintaining adequate carbohydrate intake is protective.
Reported in the research mapped here as able to provoke: Acute intermittent porphyria in people with this condition.
The source text this rests on
“Attacks are often induced by precipitating factors such as drugs, alcohol, infection, fasting or changes in sex-hormone…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:36598516
Notesconfirmed from PMID:9638723 via curation 2026-06-14 | superseded (replace) by PMID:36598516 on 2026-06-19 [carrie]
Last reviewed2026-06-19
alcohol
Alcohol can precipitate an acute attack and is best avoided.
Reported in the research mapped here as able to provoke: Acute intermittent porphyria in people with this condition.
The source text this rests on
“Attacks are often induced by precipitating factors such as drugs, alcohol, infection, fasting or changes in sex-hormone…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:36642627
Notesconfirmed from PMID:9638723 via curation 2026-06-14 | superseded (replace) by PMID:36642627 on 2026-06-19 [carrie]
Last reviewed2026-06-19
hormonal changes
Hormonal fluctuations, especially around the menstrual cycle and with some hormonal treatments, can trigger attacks.
Reported in the research mapped here as able to provoke: Acute intermittent porphyria in people with this condition.
The source text this rests on
“Attacks are often induced by precipitating factors such as drugs, alcohol, infection, fasting or changes in sex-hormone…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Supporting sourcesPMID:36598516
Notesconfirmed from PMID:9638723 via curation 2026-06-14 | superseded (replace) by PMID:36598516 on 2026-06-19 [carrie]
Last reviewed2026-06-19
What changes how it shows up
Carrying the genetic change is not the whole story. The factors below are described in the research mapped here as changing whether, or how strongly, the condition appears. They modulate how the genotype is expressed; they do not, on their own, cause or cure it.
low penetrance
Penetrance is low: only a small minority of people who carry an HMBS variant ever have acute attacks, which is why relatives can share the same variant yet differ widely in whether they are affected.
Described as modulating: Acute intermittent porphyria.
The source text this rests on
“…characterized by low…”
An excerpt quoted verbatim from the source named above, shown as recorded. The full sentence is in the linked source.
Evidence ratingweak
Confidence (0-1)0.7
Replicationunreplicated
Notesconfirmed from PMID:39188285 via curation 2026-06-14
Last reviewed2026-06-14
How to read the evidence labels
Widely acceptedSpecialists broadly agree on this.
Strong evidenceBacked by solid, repeated research.
Moderate evidenceReasonable evidence, still being confirmed.
Limited evidenceSome evidence, but not yet convincing.
Early evidenceAn early finding that needs more study.
Experts disagreeResearchers actively disagree about this.
No longer supportedLater, stronger evidence or guidance overturned this.
Where this comes from
This guide is built from 13 published source(s). Every claim above links back to one of them. Click any source ID to read the original on PubMed.
ORPHA:79276 · Orphanet/HPO annotations for Acute intermittent porphyria
PMID:17298222 · (Far) Outside the box: genomic approach to acute porphyria.
PMID:23605132 · Best practice guidelines on clinical management of acute attacks of porphyria and their complications.
PMID:39188285 · Acute intermittent porphyria: a disease with low penetrance and high heterogeneity.
PMID:39425488 · Neuralgic amyotrophy presentation of acute intermittent porphyria: A case report.
PMID:39597922 · German Real-World Experience of Patients with Diverse Features of Acute Intermittent Porphyria Treated with Givosiran.
PMID:39737264 · Acute Intermittent Porphyria in an Adolescent Patient: Diagnostic and Treatment Challenges.
PMID:7866402 · Molecular basis of acute intermittent porphyria: mutations and polymorphisms in the human hydroxymethylbilane synthase gene.
Take it further
Printed, source-linked documents built from this condition's graph — ready to bring to an appointment or attach to a coverage request. Every claim carries its published source, the same as this guide.