Management of Allergic Reactions and Anaphylaxis in Pregnancy

Authors: Haleigh Bodeau, MD (EM Resident Physician, Virginia Tech-Carilion) and Janet Young, MD (Associate Professor of Emergency Medicine, Virginia Tech Carilion School of Medicine) // Reviewed by: Christopher M. McStay, MD, FACEP, FAWM (Associate Professor, Department of Emergency Medicine, University of Colorado School of Medicine); Alex Koyfman, MD (@EMHighAK); and Brit Long, MD (@long_brit)


A 29 year-old G2P1 female at 30 weeks gestation presents to the emergency department for rash. She was diagnosed with streptococcal pharyngitis yesterday and has been taking Amoxicillin. She first noticed a faint rash that developed into urticaria and she is now complaining of abdominal discomfort, nausea, and shortness of breath. She appears uncomfortable on exam and you notice that she has diffuse urticaria and faint wheezes on pulmonary exam.  Her temperature is 98.9F, heart rate is 95 bpm, blood pressure is 94/71 mmHg, respiratory rate is 26 breaths/minute, and pulse oximetry is 98% on room air.


Data regarding the prevalence of allergic reactions and anaphylaxis in pregnant women are scarce. It is likely that greater than 10% of all pregnancies are complicated by acute urticaria.1 Recent studies suggest an incidence of 1.6 to 2.7 cases of anaphylaxis per 100,000 deliveries.2,3  Prior to labor and delivery, the most common triggers of allergic and anaphylactic reactions are similar to that of the general population. These include food allergens (e.g. peanuts, tree nuts, shellfish), latex, medications, and venom from stinging Hymenoptera insects (ants, bees, wasps, etc.).4,5 Pregnant women also experience allergic reactions to contrast media.6 During labor and delivery, the most common triggers for allergic reactions are antibiotics (especially penicillins and cephalosporins used for prevention of neonatal Group B Streptococcalinfection), oxytocin, anesthetic agents (neuromuscular blockers, general anesthetics, epidural medications), and latex.2,3,7 Breastfeeding has also been found to cause anaphylaxis, although this is rare.8-11

Presentation & Diagnosis:

Allergic and anaphylactic reactions are typically diagnosed clinically, requiring a thorough history and physical exam. Signs and symptoms of anaphylaxis can include involvement of the skin and mucosa (rash, urticaria, pruritus, edema), gastrointestinal tract (nausea, vomiting, diarrhea, abdominal discomfort), respiratory system (shortness of breath, wheezing, cough, stridor, hypoxia), and evidence of end-organ dysfunction (hypotension, hypotonia, syncope, incontinence).4,7 In pregnant patients, symptoms may also include vaginal/vulvar itching, low back pain, uterine contractions, fetal distress, and even preterm labor. Prompt diagnosis of anaphylaxis is imperative as it can be detrimental to both the mother and the developing fetus.7

Table 1. Table adapted from [4,7]

Table 2. Differential Diagnoses.


Treatment of anaphylaxis in pregnant patients is similar that of nonpregnant patients, but includes several important additional steps: 6,7

  • Airway assessment (emergent intubation if evidence of impending airway obstruction)
  • Epinephrine is the treatment of choice. Use 0.3-0.5 mg IM and repeat every 5-15 minutes as needed. Consider an epinephrine drip. (Category C)
  • Administer high-flow humidified supplemental oxygen (8-10 L via facemask, up to 100%) to increase fetal oxygenation
  • Position the patient onto their left side (or manually displace the gravid uterus to the left) to relieve compression of the vena cava and increase venous return
  • Rapid infusion of IV crystalloids for hypotension
  • Maintain a minimum maternal systolic blood pressure of 90 mmHg or MAP >65
  • Continuous electronic fetal monitoring (if possible)
  • Consider administration of adjunctive agents (albuterol, H1 antihistamines, H2 antihistamines, and glucocorticoids)
    • Albuterol 2.5-5 mg in 3 mL saline via nebulizer for resistant bronchospasm (Category C)
    • Diphenhydramine 25-50 mg IV or cetirizine 10 mg IV for urticaria and pruritus (Category B)
    • Famotidine 20 mg IV (Category B)
    • Methylprednisolone 125 mg IV (Category C)*
  • Consult OB/GYN and consider performing emergency caesarean delivery for anaphylaxis that is refractory to medical management or for fetal distress (persistent late decelerations on fetal heart monitoring) if greater than 22 weeks gestation

*High-dose glucocorticoids may increase the risk of cleft-palate (if used in the first trimester), premature rupture of membranes (PROM), intrauterine growth restriction (IUGR), maternal hypertension, and gestational diabetes. These medications should be used with caution.

Treatment of urticaria and atopic dermatitis without evidence of anaphylaxis usually involves oral antihistamines (10 mg Cetirizine or Loratadine daily). Emollients and topical corticosteroids (hydrocortisone 0.5 – 2.5% BID) are also typically used for atopic dermatitis. Severe flares of either can be treated with oral glucocorticoids (prednisone is preferred in pregnancy but should be avoided in the first trimester if possible).12

Take Home Points:

  • Allergic reactions are common in pregnancy.
  • Anaphylaxis and allergic reactions are diagnosed clinically and require a thorough history and physical exam.
  • Epinephrine is the first-line treatment for anaphylaxis in pregnant patients. Adjuncts including antihistamines, albuterol, and glucocorticoids may also be used.
  • Anaphylaxis in pregnancy requires extended maternal-fetal monitoring and positioning of the patient on their left side.

References/Further Reading:

  1. Kadar L, Kivity S. Urticaria and Angioedema in Pregnancy. Current Dermatology Reports. 2013; 2(4), 236–242.
  2. Mulla ZD, Ebrahim MS, Gonzalez JL. Anaphylaxis in the obstetric patient: analysis of a statewide hospital discharge database. Ann Allergy Asthma Immunol. 2010;104(1):55-59. doi:10.1016/j.anai.2009.11.005
  3. McCall SJ, Bunch KJ, Brocklehurst P, et al. The incidence, characteristics, management and outcomes of anaphylaxis in pregnancy: a population-based descriptive study. BJOG. 2018;125(8):965-971. doi:10.1111/1471-0528.15041
  4. Shaker MS, Wallace DV, Golden DBK, et al. Anaphylaxis-a 2020 practice parameter update, systematic review, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) analysis. J Allergy Clin Immunol. 2020;145(4):1082-1123. doi:10.1016/j.jaci.2020.01.017
  5. Simons FE, Ebisawa M, Sanchez-Borges M, et al. 2015 update of the evidence base: World Allergy Organization anaphylaxis guidelines. World Allergy Organ J. 2015;8(1):32. Published 2015 Oct 28. doi:10.1186/s40413-015-0080-1
  6. Sikka A, Bisla JK, Rajan PV, et al. How to Manage Allergic Reactions to Contrast Agent in Pregnant Patients. AJR Am J Roentgenol. 2016;206(2):247-252. doi:10.2214/AJR.15.14976
  7. Simons FE, Schatz M. Anaphylaxis during pregnancy. J Allergy Clin Immunol. 2012;130(3):597-606. doi:10.1016/j.jaci.2012.06.035
  8. Durgakeri P, Jones B. A rare case of lactation anaphylaxis. Australas Med J. 2015;8(3):103-105. Published 2015 Mar 31. doi:10.4066/AMJ.2015.2349
  9. Pescatore R, Mekkaoui S, Duffell B, Riviello R. A Case of Lactation Anaphylaxis. Cureus. 2019;11(8):e5497. Published 2019 Aug 27. doi:10.7759/cureus.5497
  10. MacDonell JW, Ito S. Breastfeeding anaphylaxis case study. J Hum Lact. 1998;14(3):243-244. doi:10.1177/089033449801400314
  11. Shank JJ, Olney SC, Lin FL, McNamara MF. Recurrent postpartum anaphylaxis with breast-feeding. Obstet Gynecol. 2009;114(2 Pt 2):415-416. doi:10.1097/AOG.0b013e3181a20721
  12. Schatz, M. Recognition and management of allergic disease during pregnancy. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc. Accessed July 9, 2020.

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