Are fish oil supplements safe in finned fish-allergic patients?

Design

Pilot study

N= 6

Objective

To determine if finned fish–allergic patients could safely tolerate fish oil supplements

Study Groups

Patients with finned-fish allergy (N= 6)

Inclusion Criteria

Patients allergic to finned fish recruited on voluntarily basis

Exclusion Criteria

N/A

Methods

Patients were recruited by advertising. Reported symptoms of patients included throat constriction, urticaria, and angioedema. Included patients were given percutaneous skin tests with histamine, saline, standard commercial finned-fish allergen extracts (catfish, cod, mackerel, salmon, sardine, and tuna) and two fish oil supplements (undiluted, unfiltered liquid extracted from Nature’s Bounty and Natrol
soft gels via syringe). Patients with skin tests found to be positive for at least one finned-fish extract and negative to both supplements were given an oral challenge of each supplement. Oral challenge, consisting of 1 soft gel, was given 1 hour apart. Vitals were compared between baseline and at 20-min intervals following challenge, while spirometry was compared at baseline and 1 hour after challenge. 

Duration

N/A

Outcome Measures

Adverse reactions

Patients and Results

Skin prick tests 

Patients/age/sex

Fish Oil 1

(Natrol)

Fish Oil 2

(Nature's Bounty)

23-year M

36-year M

64-year F

46-year F

45-year M

37-year F

Adverse Events

Study Author Conclusions

In this pilot study, finned-fish-sensitive patients tolerated fish oil supplements.

InpharmD Researcher Critique

This study was limited to an extremely small sample size, limiting generalizability of results. Additionally, patients were allergic to finned-fish specifically, not shellfish. 

Flushing and Pruritus Secondary to Prescription Fish Oil Ingestion in a Patient with Allergy to Fish

Design

Case presentation

A 65-year-old female with a documented history of seafood allergy, including shellfish and tuna, was prescribed omega-3-acid ethyl esters (2 grams twice daily) by her hepatologist for elevated triglyceride levels. Four days after initiating the prescription fish oil product, she presented to the emergency department with symptoms of chest tightness, shortness of breath, upper extremity tingling, facial flushing, and severe pruritus. These symptoms were only minimally relieved by self-administered diphenhydramine.

The patient discontinued the fish oil capsules two days before a primary care visit and reported ongoing flushing and pruritus at that time. Laboratory evaluation showed an elevated serum IgE concentration. All symptoms resolved within three days after discontinuing the fish oil and discarding all medications and containers that had been in contact with the capsules. Notably, the adverse reaction was evaluated using the Naranjo probability scale and deemed probably related to the fish oil product. The patient continued other medications, including niacin, during the evaluation and recovery period without recurrence of symptoms.

Study Author Conclusions

Due to the patient’s allergic history, timing of onset/offset of the reaction, laboratory evidence, and the use of the Naranjo probability scale, prescription fish oil capsules were deemed the probable cause of this patient’s pruritus and flushing of the face and trunk. Practitioners and patients should always ensure they have an updated list of allergies within the patient’s medical record that includes medications as well as foods and food additives.

Fish-oil capsule ingestion

Design

Case presentation

A 45-year-old woman with a history of urticaria and lip angioedema to crab, as well as allergic rhinitis and asthma, experienced her first anaphylactic reaction following the ingestion of an omega-3-6-9 capsule. This reaction manifested with significant tongue, throat, and facial swelling, stridor, and shortness of breath, requiring immediate medical intervention at a rural emergency department. Despite being administered epinephrine and other medications, her symptoms recurred multiple times, leading to ongoing management challenges. Initial treatment included 1 mg of intramuscular epinephrine, 50 mg of diphenhydramine, nebulized salbutamol, and intravenous methylprednisolone. She showed rapid initial improvement, avoiding intubation, but experienced a biphasic reaction with recurrent stridor, requiring additional epinephrine. Continued management involved a regimen of hydroxyzine, ranitidine, diphenhydramine, montelukast, cetirizine, and nebulized medications. Despite these measures, she continued to experience episodes of anaphylaxis with upper respiratory tract symptoms. Due to the severity and recurrence of her symptoms, along with unknown metabolism details of the omega-3-6-9 product, she was transferred to an urban tertiary care center's ICU. There, she was stabilized over five days with similar treatment. Investigations such as C1 esterase inhibitor and immunoglobulin levels were normal. She was discharged with a referral to an allergist for further evaluation and management. 

Study Author Conclusions