Most allergy medications are not off-limits during pregnancy, but the timing and type matter. The general approach is to start with drug-free strategies, use nasal sprays as a next step, and reserve oral antihistamines for symptoms that don’t respond to simpler measures. The first trimester calls for the most caution, since that’s when fetal organs are forming.
Make Sure It’s Actually Allergies
Pregnancy itself causes nasal congestion in a large number of women, a condition called pregnancy rhinitis. It typically shows up after the 20th week of gestation, lasts at least six weeks, and clears up within two weeks of delivery. The key difference: pregnancy rhinitis causes stuffiness without the sneezing, itchy eyes, or watery nose that come with true allergies. It also doesn’t respond well to antihistamines.
If your congestion started in the second or third trimester and stuffiness is your only symptom, hormonal swelling of your nasal passages is the more likely cause. Allergic rhinitis, by contrast, tends to follow seasonal patterns or worsen around specific triggers like dust, pet dander, or pollen, and it typically brings sneezing and itchiness along with it. Knowing which one you’re dealing with shapes what treatment actually helps.
Start With Drug-Free Options
Saline nasal rinses are the safest first step and surprisingly effective. In a randomized study of pregnant women with seasonal allergies, those who used a hypertonic saline rinse three times daily saw a statistically significant improvement in symptoms within two weeks. They also needed fewer antihistamines overall. A neti pot or squeeze bottle with a premixed saline packet works well. Use distilled or previously boiled water to avoid introducing bacteria.
Beyond saline rinses, basic environmental controls make a real difference:
- Keep windows closed during high pollen counts and use air conditioning instead
- Shower and change clothes after spending time outdoors
- Use dust mite covers on pillows and mattresses
- Run a HEPA filter in your bedroom
- Limit pet access to sleeping areas if animal dander is a trigger
These steps won’t eliminate symptoms, but they can reduce the medication you need.
Nasal Steroid Sprays: The Preferred Medication
If saline rinses aren’t enough, steroid nasal sprays are considered the most effective option with a strong safety profile. The medication acts locally in the nasal passages, so very little reaches your bloodstream or the fetus. A safety review found no significant association with organ malformations for budesonide, fluticasone, beclomethasone, or mometasone when used at recommended doses.
One exception: intranasal triamcinolone has been linked to respiratory tract defects and is best avoided. Budesonide has the most pregnancy safety data behind it and is often the first choice. Fluticasone and mometasone are also considered safe options. These sprays take a few days of consistent use to reach full effect, so don’t expect instant relief the way you would from a decongestant.
Which Oral Antihistamines Are Safest
The American College of Obstetricians and Gynecologists and the American College of Allergy, Asthma and Immunology recommend chlorpheniramine as the first-choice oral antihistamine during pregnancy. It’s a first-generation antihistamine, which means it can cause drowsiness. If that’s a problem, or if it doesn’t control your symptoms, cetirizine (Zyrtec) and loratadine (Claritin) are the preferred second-generation options. Both are classified as Category B, meaning animal studies showed no harm and the available human data support their safety.
The key timing consideration: all oral antihistamines are best avoided in the first trimester when possible. Organ development is most active during those early weeks, and no antihistamine has been classified as completely safe during that window. If your allergies are manageable with saline rinses and nasal sprays through the first 12 weeks, that’s the ideal approach. After the first trimester, cetirizine and loratadine are widely used with confidence.
What About Diphenhydramine (Benadryl)?
Diphenhydramine is commonly used, but the data is more mixed. Several studies found no increased chance of birth defects, while a few suggested a slightly higher risk with first-trimester use, though no consistent pattern has emerged. Occasional use at recommended doses does not appear to raise the risk of preterm delivery or low birth weight.
The bigger concerns show up with heavy or prolonged use. Reports of uterine contractions and, rarely, fetal complications have been linked to diphenhydramine in the third trimester, typically when taken at higher-than-recommended doses or for extended periods. Babies exposed daily throughout pregnancy have occasionally shown temporary withdrawal symptoms like tremors and diarrhea after birth. For occasional relief, it’s generally considered acceptable, but it’s not the best choice for daily allergy management during pregnancy.
Decongestants: Proceed With Caution
Oral decongestants like pseudoephedrine (Sudafed) occupy a gray area. A large population-based cohort study found that first-trimester pseudoephedrine exposure was not an independent risk factor for major congenital malformations overall. However, an earlier case-control study reported a possible increased risk of gastroschisis (a type of abdominal wall defect) with first-trimester use, with an odds ratio of 1.8. Other studies did not replicate that finding. The evidence is mixed enough that most practitioners suggest avoiding oral decongestants in the first trimester and using them sparingly afterward.
Topical decongestant sprays (like oxymetazoline) deliver less medication systemically, but they carry their own problem: rebound congestion if used for more than three consecutive days. This can create a cycle of worsening stuffiness that’s especially frustrating during pregnancy.
Allergy Shots During Pregnancy
If you were already receiving allergy immunotherapy (allergy shots) before becoming pregnant, you can safely continue your maintenance dose. Both American and European allergy guidelines support this. Continuing treatment avoids the symptom flare that comes with stopping mid-course.
Starting allergy shots during pregnancy is a different story. Guidelines discourage initiating immunotherapy while pregnant because the dose-escalation phase carries a small risk of anaphylaxis, which poses serious dangers to both mother and fetus. The one exception is for women with a history of life-threatening reactions to insect stings, where the benefit of venom immunotherapy may outweigh the risk.
Why Treating Allergies Matters for Pregnancy
Some women hesitate to take any medication, assuming untreated allergies are the safer path. For mild, occasional symptoms, that’s reasonable. But if you have allergic rhinitis alongside asthma, leaving allergies unmanaged can worsen asthma control. Uncontrolled asthma during pregnancy is associated with low birth weight, growth restriction, and complications linked to reduced oxygen reaching the fetus. Upper airway congestion from allergies can trigger coughing and wheezing episodes that compound asthma symptoms. Treating the allergies isn’t just about comfort; it protects breathing function that your baby depends on.
Herbal Supplements to Avoid
Butterbur, one of the most studied herbal remedies for allergies, contains compounds called pyrrolizidine alkaloids that can cause birth defects and liver damage. Even “PA-free” butterbur products lack sufficient safety data during pregnancy. Quercetin and stinging nettle, two other popular natural allergy supplements, similarly lack pregnancy-specific safety studies. The absence of evidence isn’t evidence of safety, and herbal products are not regulated with the same rigor as medications. Saline rinses are the safest natural approach by a wide margin.
A Practical Treatment Ladder
The simplest way to think about allergy management during pregnancy is as a step-up approach:
- Step 1: Allergen avoidance and saline nasal rinses, which are safe throughout all trimesters
- Step 2: Add a steroid nasal spray like budesonide, safe at any point in pregnancy at recommended doses
- Step 3: After the first trimester, add cetirizine or loratadine if nasal sprays alone aren’t enough
- Step 4: For breakthrough symptoms, occasional diphenhydramine or chlorpheniramine at standard doses
Each step adds a little more medication only when the previous level isn’t controlling symptoms. This minimizes exposure while keeping you comfortable enough to sleep, breathe, and function normally, all of which matter for a healthy pregnancy.