Several allergy medications have reassuring safety data in pregnancy, though the options narrow compared to what you might take when not pregnant. Antihistamines are the most studied class, with large analyses covering hundreds of thousands of pregnancies showing no meaningful increase in birth defect risk. Nasal steroid sprays and saline rinses are also considered front-line options. The picture gets murkier with oral decongestants, which carry enough concern that most guidelines push them to a second-line role or suggest avoiding them entirely. The real risk during pregnancy often comes not from carefully chosen medication but from leaving allergies untreated, especially when asthma is also in the picture.
Why Allergies Can Feel Worse During Pregnancy
If your nose feels more stuffed up than usual while pregnant, you are not imagining it. Pregnancy triggers a cascade of immune shifts that favor the kind of inflammatory response behind allergic symptoms. The immune system dials up what researchers call type-2 responses, the same branch that drives hay fever and allergic asthma, which can make existing allergies flare or feel harder to control.1PubMed. Management of allergic diseases in pregnancy On top of that, about one in four to one in three pregnant women develop what is sometimes called rhinitis of pregnancy, a persistent nasal congestion that shows up most often in the second trimester and goes away after delivery.2PubMed Central. Rhinitis of Pregnancy and Hormonally Induced Rhinitis This hormonal congestion stacks on top of any allergic rhinitis you already have, and the combination can significantly erode quality of life. Women with preexisting allergic rhinitis score worse on symptom questionnaires during the second and third trimesters than women without that history.3PubMed. Rhinosinusitis-related quality of life during pregnancy
All of this makes a strong case for treating allergies during pregnancy rather than toughing it out. Poor nasal breathing disrupts sleep, aggravates fatigue that is already a constant companion in pregnancy, and can worsen coexisting asthma. The goal is to find treatments that keep you comfortable without posing unacceptable risk to the developing baby.
Antihistamines With the Most Reassuring Data
Antihistamines are the backbone of allergy treatment in pregnancy, and here the evidence is genuinely large. A meta-analysis covering more than 200,000 pregnant women found no increase in the risk of birth defects with antihistamine use.4PubMed Central. A review of antihistamines used during pregnancy That is a reassuring number, and it spans both older and newer antihistamines.
Among the older, first-generation antihistamines, chlorpheniramine and dexchlorpheniramine have the longest safety track record and are considered the safest choices in their class.5PubMed Central. A review of antihistamines used during pregnancy The trade-off is that these drugs make you drowsy. For many pregnant women who are already battling fatigue, a sedating antihistamine taken at bedtime is tolerable or even welcome, but daytime use can be impractical.
The newer, second-generation antihistamines rarely cause drowsiness, which is why most people prefer them outside of pregnancy. Cetirizine (Zyrtec) and loratadine (Claritin) have accumulated the most pregnancy safety data in this group. Fexofenadine (Allegra) was less studied until a large study directly compared it against cetirizine in nearly 10,000 pregnancies and found no meaningful difference in major birth defects, miscarriage, preterm birth, or stillbirth between the two drugs.6PubMed Central. Association Between Fexofenadine Use During Pregnancy and Fetal Outcomes The birth defect rate was around 4% in both groups, consistent with the background rate in the general population. That study went a long way toward establishing fexofenadine as a reasonable option during pregnancy when cetirizine or loratadine are not a good fit.
Nasal Sprays and Topical Options
Nasal corticosteroid sprays are a mainstay for allergic rhinitis, and pregnancy does not necessarily mean you have to stop using them. The newer sprays like budesonide, fluticasone, and mometasone have very little absorption into the bloodstream. Studies measuring maternal cortisol levels and fetal growth in women using these sprays found no detectable effect on either, which is reassuring.7PubMed Central. Management of rhinosinusitis during pregnancy: systematic review and expert panel recommendations Budesonide has the most data behind it in pregnancy and is often the go-to recommendation. That said, the evidence base for newer sprays, while encouraging, is not yet as deep as it is for antihistamines, so the standard advice is to use the lowest effective dose.
Saline nasal rinses deserve a special mention because they carry essentially zero pharmacological risk. A randomized study in pregnant women with seasonal allergic rhinitis found nasal rinsing to be both safe and effective at reducing symptoms.8International Archives of Allergy and Immunology. Nasal Lavage in Pregnant Women with Seasonal Allergic Rhinitis: A Randomized Study For mild symptoms, a neti pot or squeeze-bottle saline rinse might be all you need. For moderate-to-severe allergies, saline rinses work well as an add-on that lets you keep your medication dose lower.
Oral Decongestants and Why Caution Is Warranted
This is the category where pregnancy changes the calculation most. Pseudoephedrine and phenylephrine, the active ingredients in Sudafed and many cold formulas, work by constricting blood vessels. That mechanism raises theoretical concerns about blood flow to the uterus, and the data is not entirely reassuring. A systematic review and meta-analysis of observational studies found that pseudoephedrine and the related compound phenylpropanolamine were associated with roughly a 50% higher risk of gastroschisis, a birth defect in which the intestines develop outside the baby’s body.9PubMed Central. Medication use during pregnancy and the risk of gastroschisis: a systematic review and meta-analysis of observational studies Gastroschisis is rare to begin with, so a 50% relative increase still translates to a small absolute risk, but it is enough to make experts cautious.
Most guidelines classify oral and topical decongestants as second-line therapy during pregnancy, appropriate only for short-term use when safer alternatives are not providing relief.10American Journal of Rhinology. Treatment of Allergic Rhinitis during Pregnancy If you used pseudoephedrine a few times before realizing you were pregnant, the absolute risk is low enough that there is no reason to panic. But as an ongoing allergy strategy, antihistamines and nasal sprays are a better foundation.
Leukotriene Receptor Antagonists
Montelukast (Singulair) is widely prescribed for both allergies and asthma, and many women wonder whether they need to stop it during pregnancy. The available evidence is encouraging. A Japanese cohort study comparing over 200 pregnancies exposed to leukotriene receptor antagonists to controls found a major birth defect rate under 2% in the exposed group, with no statistical link between the medication and defects.11PubMed. The safety of pranlukast and montelukast during the first trimester of pregnancy: A prospective, two-centered cohort study in Japan There was also no difference in miscarriage, preterm birth, or low birth weight. For women already on montelukast before pregnancy, particularly those with coexisting asthma, most experts lean toward continuing it rather than disrupting a regimen that is working.
Cromolyn sodium, an older mast-cell stabilizer available as a nasal spray, carries a safety profile during pregnancy based largely on animal reproduction studies, with no concerning signals.12PubMed. Asthma controller therapy during pregnancy It is less commonly used today because antihistamines and nasal steroids tend to work better, but it remains an option if you are looking to minimize systemic drug exposure.
The Asthma Connection
Allergic rhinitis and asthma frequently travel together, and pregnancy is a particularly bad time to let either go uncontrolled. Poorly managed nasal allergies can trigger or worsen asthma symptoms, and uncontrolled asthma during pregnancy carries real risks including preeclampsia, preterm delivery, and low birth weight. The National Asthma Education and Prevention Program’s working group on asthma and pregnancy specifically recommends treating allergic rhinitis as part of optimal asthma management during pregnancy.13PubMed. Treating asthma and comorbid allergic rhinitis in pregnancy In this context, the risk of leaving allergies untreated is often greater than the risk of the medications themselves.14PubMed. The management of asthma and rhinitis during pregnancy
This is an important reframe for anyone whose instinct is to stop all medication the moment the pregnancy test turns positive. For women with moderate or severe allergic rhinitis, especially those with coexisting asthma, untreated disease is not the neutral baseline it might seem. It is an active risk.
What About Allergy Shots and Immunotherapy
If you are already receiving allergy shots (subcutaneous immunotherapy) or sublingual immunotherapy, there is no need to stop abruptly when you find out you are pregnant. A review covering 453 pregnancies in women who continued immunotherapy found no significant increase in prematurity, congenital malformations, high blood pressure, or perinatal deaths compared to controls.15PubMed Central. Allergen immunotherapy in pregnancy Among the small number who experienced systemic allergic reactions during immunotherapy sessions, none had fetal complications. An older but frequently cited retrospective study of 121 pregnancies in women receiving immunotherapy reached the same conclusion, finding no elevated rates of prematurity, miscarriage, neonatal death, or birth defects beyond what would be expected in the general population.16Journal of Allergy and Clinical Immunology. The safety of immunotherapy during pregnancy
The conventional guidance, however, is to maintain a stable dose rather than escalate it during pregnancy. The concern is not that immunotherapy harms the fetus directly, but that a systemic allergic reaction (which is more likely at higher doses) could cause a blood pressure drop that temporarily reduces blood flow to the placenta. Starting immunotherapy from scratch during pregnancy is generally discouraged for the same reason. If you have been wanting to begin allergy shots, it is usually better to wait until after delivery.
Anaphylaxis and Epinephrine
Severe allergic reactions do not stop being possible just because you are pregnant, and the treatment remains the same: epinephrine, injected into the thigh. There is sometimes hesitation around using an EpiPen during pregnancy because epinephrine constricts blood vessels and could theoretically affect uterine blood flow. But the evidence indicates that the real danger is in not treating anaphylaxis. A case report describing epinephrine use during a severe allergic reaction in pregnancy found that the fetus tolerated the injection well, with continuous monitoring showing no signs of fetal distress.17PubMed. Fetal response to intramuscular epinephrine for anaphylaxis during maternal penicillin desensitization for secondary syphilis Treatment protocols for maternal anaphylaxis follow the same dosing as for non-pregnant adults, with repeat injections every five to fifteen minutes if symptoms persist.18PubMed Central. Management of maternal anaphylaxis in pregnancy: a case report
If you carry an EpiPen for food allergies, insect stings, or any other trigger, keep carrying it during pregnancy. Anaphylaxis left untreated is far more dangerous to both you and the baby than a dose of epinephrine.
How Pregnancy Changes the Way Your Body Handles Drugs
Even if you stay on the same allergy medication at the same dose, pregnancy can change how your body processes it. Plasma volume expands by roughly 40% during pregnancy, which dilutes drug concentrations in the blood. Kidney filtration increases by 30 to 50%, meaning drugs cleared through the kidneys are flushed out faster. Liver enzymes that break down medications also shift, with some speeding up and others slowing down.19PubMed Central. Drugs in pregnancy: Pharmacologic and physiologic changes that affect clinical care The practical result is that a dose that worked well before pregnancy might become less effective. If you feel like your allergy medicine has stopped working as well, this is a legitimate pharmacological explanation, not just a placebo effect or worsening allergies. Your provider may need to adjust timing or dosing rather than switch drugs entirely.
The FDA Labeling You Might See Online
If you search for allergy drug safety in pregnancy, you will inevitably encounter references to “Category B” or “Category C.” These letter grades come from the old FDA pregnancy category system, which was officially replaced in 2015 by a narrative labeling format that provides more detailed information about risks.20PubMed. Clinicians’ Perspective of the New Pregnancy and Lactation Labeling Rule (PLLR): Results from an AAAAI/FDA Survey The old letter categories were misleading because they lumped together drugs with very different amounts and types of evidence. A “Category B” rating could mean a drug had strong human safety data or simply that animal studies looked fine but nobody had studied it in pregnant women. The new system provides actual summaries of what is known. That said, the transition is still ongoing, and many drug package inserts have not yet been fully updated, so you may still see the letters referenced in online databases and older information sheets.
Breastfeeding After Delivery
Allergy season does not end at delivery, and if you are breastfeeding, the question of medication safety continues. A systematic review of antihistamine transfer into breast milk found that all studied antihistamines passed into milk at very low levels, well below the thresholds generally considered concerning. The relative infant dose ranged from under 1% to about 4.5%, with all antihistamines falling below the 5% threshold used as a safety benchmark.21PubMed. Antihistamine use during breastfeeding with focus on breast milk transfer and safety in humans: A systematic literature review Despite this, most drug labels in the United States and Europe still recommend avoiding antihistamines while breastfeeding, citing a lack of data rather than evidence of harm. This is a good example of package-insert language being more conservative than the actual evidence. The second-generation antihistamines (cetirizine, loratadine, fexofenadine) are generally preferred while nursing because they cause less sedation, which matters when your infant depends on you being alert.
Herbal and “Natural” Allergy Remedies
The instinct to reach for something herbal or natural during pregnancy is understandable but deserves scrutiny. Many people assume that natural means safer, yet herbal products are not tested to the same standard as pharmaceutical drugs, and pregnancy data on most herbs is thin or contradictory. A systematic review of herbal medicines used by pregnant women in Asian countries identified 33 commonly used herbs, and of those, only 13 could be classified as safe. Eight were considered potentially harmful, and seven lacked enough data to classify at all.22PubMed Central. Safety classification of herbal medicines used among pregnant women in Asian countries: a systematic review Ginger is among the better-studied options and appears safe at doses under 1,000 mg per day, though it is primarily studied for nausea rather than allergies.23PubMed Central. Herbal Medicines—Are They Effective and Safe during Pregnancy? For popular herbal allergy remedies like butterbur, stinging nettle, or high-dose quercetin, the pregnancy safety data is essentially nonexistent. Ironically, you often have better safety information for a pharmaceutical antihistamine studied in 200,000 pregnancies than for an herbal supplement marketed as “gentle” or “natural.”
Timing and the First Trimester
Any medication taken during pregnancy has the potential to affect fetal development, but the timing of exposure matters. The first trimester is the most sensitive period because major organ systems are forming during those early weeks.24PubMed Central. We Don’t Know What We Don’t Study: The Case for Research on Medication Effects in Pregnancy This is why the conversation about medication safety often centers on early pregnancy, and why some women try to avoid all drugs during those first twelve weeks. But exposures during the second and third trimesters are not consequence-free either; they can influence growth, functional development, and other outcomes.
For allergy medications specifically, the large-scale safety data referenced earlier includes first-trimester exposures and still shows no meaningful increase in birth defects. That does not erase the general principle of using the lowest effective dose, but it does mean that a pregnant woman who took cetirizine before she knew she was pregnant has no reason for alarm. The evidence is consistent and covers the most sensitive window. A practical approach is to start with non-drug measures like saline rinses and allergen avoidance, add a well-studied antihistamine or nasal steroid if needed, and save decongestants for the worst flares if they are needed at all. Talking to your provider about your specific allergy pattern and any coexisting conditions like asthma is the most reliable way to land on a regimen that keeps both you and the baby as safe as possible.