What are the recommended treatments for allergies in patients with Hereditary Hemorrhagic Telangiectasia (HHT)?

Treatment of Allergies in Patients with Hereditary Hemorrhagic Telangiectasia

Direct Answer

Standard allergy treatments including antihistamines, corticosteroids, and epinephrine can be safely used in HHT patients, as these medications do not worsen the underlying vascular malformations or bleeding tendency characteristic of HHT. 1

Key Clinical Distinction

The critical point is understanding that HHT is not an allergic or histamine-mediated condition—it is a vascular disorder caused by mutations in genes affecting blood vessel formation (ENG, ACVRL1, or SMAD4). 2, 3 The confusion may arise because:

• HHT causes recurrent epistaxis and bleeding that might superficially resemble allergic symptoms 2
• However, the bleeding mechanism in HHT involves abnormal blood vessel formation and fragility, not histamine release or bradykinin generation 1

Safe Use of Allergy Medications in HHT

Antihistamines and Corticosteroids

• Antihistamines and corticosteroids are safe to use for true allergic conditions in HHT patients, as these medications do not affect the vascular malformations or bleeding pathways involved in HHT 1
• These medications are ineffective for treating HHT-related bleeding (which is not histamine-mediated), but they do not worsen HHT symptoms 1

Epinephrine

• Epinephrine is safe for anaphylaxis or severe allergic reactions in HHT patients and should not be withheld when indicated for true allergic emergencies 1
• While epinephrine does not treat HHT-related bleeding, it may provide temporary vasoconstriction benefit without causing harm 1

Important Caveats for HHT Patients

Medications to Avoid or Use Cautiously

• Avoid dual antiplatelet therapy and combination antiplatelet/anticoagulation therapy where possible, as these significantly increase bleeding risk in HHT patients 1
• If anticoagulation is required, prefer heparin agents or vitamin K antagonists over direct oral anticoagulants (DOACs), as DOACs may be less well tolerated due to increased bleeding risk 1
• Avoid estrogen-containing birth control pills and estrogen replacement therapy, as these increase swelling frequency in some vascular disorders, though this evidence comes from hereditary angioedema studies 1

Nasal Care Considerations

• For HHT patients with allergic rhinitis, nasal moisturization with saline gels and humidification is the foundation of care, as this prevents epistaxis from fragile telangiectasias regardless of the trigger 4
• 74% of HHT patients using nasal creams/sprays/oils reported fewer bleeding episodes compared to those without nasal care 5

Clinical Pitfall to Avoid

Do not mistake HHT-related epistaxis for allergic rhinitis. The key distinguishing features are:

• HHT epistaxis is spontaneous, recurrent, and often severe, occurring in >90% of adults with HHT 2, 3
• HHT epistaxis typically begins around age 11 and worsens with age 2
• HHT patients have visible telangiectasias on lips, oral cavity, fingers, and nose 2
• If a patient presents with "allergic symptoms" but has characteristic telangiectasias and family history, apply the Curaçao diagnostic criteria for HHT 2

When Allergy Treatment Fails to Control Symptoms

If nasal symptoms persist despite appropriate allergy treatment, consider that the underlying issue is HHT-related bleeding requiring HHT-specific management:

• First-line: Nasal moisturization with saline gels and humidification 4
• Second-line: Oral tranexamic acid (17.3% reduction in epistaxis duration) 4
• Third-line: Local ablative therapies (laser treatment, electrosurgery) 4
• Fourth-line: Systemic bevacizumab for severe refractory bleeding (50% reduction in epistaxis severity score) 4