Antihistamines in Pregnancy: What’s Safe and What to Avoid

When you’re pregnant and your nose won’t stop running, your eyes are itchy, or your skin is breaking out in hives, the last thing you want is to suffer through it. But popping an over-the-counter antihistamine feels risky. Is it safe? Could it hurt the baby? These aren’t just worries-they’re real questions every pregnant person with allergies faces.

Why Antihistamines Even Matter During Pregnancy

Allergies don’t take a break when you’re pregnant. In fact, about 20% of pregnant people experience worsened allergy symptoms. Runny nose, sneezing, itchy eyes-these aren’t just annoyances. If left untreated, they can lead to poor sleep, trouble eating, increased stress, and even trigger asthma flare-ups. That’s not just bad for you-it can affect your baby’s growth and development too.

The goal isn’t to avoid all medication. It’s to find the safest way to feel better. That means knowing which antihistamines have real data behind them, which ones to skip, and when to reach for something other than a pill.

First-Generation vs. Second-Generation: The Big Difference

Not all antihistamines are the same. They fall into two main groups, and the difference matters a lot during pregnancy.

First-generation antihistamines like chlorpheniramine (ChlorTrimeton), diphenhydramine (Benadryl), and dexchlorpheniramine have been around for decades. They cross into the brain, which is why they make you sleepy. That’s their downside. But they also mean we have a lot of data on them. Studies tracking thousands of pregnancies show no increase in birth defects with chlorpheniramine or diphenhydramine. The American College of Obstetricians and Gynecologists (ACOG) lists chlorpheniramine as a safe option. The same goes for dexchlorpheniramine.

Second-generation antihistamines like loratadine (Claritin), cetirizine (Zyrtec), and fexofenadine (Allegra) were designed to avoid drowsiness. They don’t cross the blood-brain barrier easily. That’s great for daily life. But they’re newer, so there’s less long-term data.

Here’s the good news: the data we do have is reassuring. A large CDC study looking at over 14 antihistamines and more than 60 types of birth defects found no consistent pattern of harm. Loratadine and cetirizine are now recommended by the Mayo Clinic as first-line choices for mild allergy symptoms during pregnancy. ACOG’s March 2025 update says these newer drugs “may also be safe.”

What’s the Safest Choice?

If you need an oral antihistamine, here’s what the experts agree on:

• Chlorpheniramine - Longest track record. Safe. Causes drowsiness.
• Loratadine (Claritin) - Non-sedating. Strong safety data. First choice for many doctors.
• Cetirizine (Zyrtec) - Also non-sedating. Used widely in pregnancy. No red flags in studies.

These three are the most commonly recommended. Avoid hydroxyzine (Atarax), especially in the first trimester. A small number of cases in the CDC’s National Birth Defects Prevention Study linked it to rare heart defects, though the sample size was tiny. Better to skip it unless there’s no other option.

What to Avoid Completely

Not all allergy meds are antihistamines. Many OTC products combine antihistamines with decongestants like pseudoephedrine (Sudafed). That’s where things get risky.

Pseudoephedrine has been tied to a small but real increase in abdominal wall birth defects-like gastroschisis-when used in the first trimester. ACOG says: don’t use it during the first 3 months. Mayo Clinic says if you absolutely need it later in pregnancy, the dose should be 30-60 mg every 4-6 hours, not to exceed 240 mg a day. And only if you don’t have high blood pressure.

Also skip phenylephrine. It’s in many “pregnancy-safe” cold meds, but there’s almost no safety data for it in pregnancy. Stick to the ones with clear evidence.

There’s More Than Just Pills

Sometimes, the best treatment isn’t a pill at all. For nasal symptoms like congestion or post-nasal drip, steroid nasal sprays are often more effective and safer.

Budesonide (Rhinocort), fluticasone (Flonase), and mometasone (Nasonex) are all classified as Category B-meaning no risk found in animal studies and no evidence of harm in human studies. AAFP gives them an evidence rating of B, same as chlorpheniramine. These sprays act locally. Very little enters your bloodstream, so even less reaches your baby.

For skin issues like eczema or hives, topical antihistamines (lotions or creams) are generally safe. But avoid oral antihistamines unless the rash is widespread or severe.

When to Use Them-and When to Hold Off

You don’t need to take an antihistamine just because you’re sneezing. Start with non-drug options:

• Use saline nasal sprays or rinses
• Keep windows closed during high pollen season
• Wash bedding in hot water weekly
• Use an air purifier in your bedroom

If symptoms still interfere with sleep, eating, or mood, then it’s time to consider medication. The key word here is interfere. If you’re not sleeping because your nose is blocked, or you’re skipping meals because your throat is itchy, then the risk of not treating is higher than the risk of treatment.

Start with the lowest effective dose. Take it only when you need it. Don’t take it daily unless your doctor says so.

What About Newer Antihistamines?

Levocetirizine (Xyzal) and desloratadine (Clarinex) are newer versions of cetirizine and loratadine. They’re more potent. But here’s the catch: there’s even less pregnancy data on them.

If you’ve been taking one of these before pregnancy and your allergies are severe, talk to your doctor. Don’t stop cold turkey-your symptoms might get worse. But if you’re starting from scratch, stick with loratadine or cetirizine. They’ve been studied more.

What the Experts Really Say

The American College of Allergy, Asthma & Immunology (ACAAI) says this clearly: “Antihistamines should not be withheld from pregnant women if they are needed to control symptoms.”

That’s the bottom line. Untreated allergies can lead to complications. Poor sleep = higher stress hormones. Chronic congestion = more sinus infections. Worsening asthma = lower oxygen for the baby.

The goal isn’t zero risk. It’s minimal risk with maximum benefit. Chlorpheniramine, loratadine, and cetirizine are your best bets. Steroid sprays are often better for nasal symptoms. Avoid decongestants in the first trimester. Skip hydroxyzine.

Always Talk to Your Doctor First

No matter what you read online, never start or stop a medication during pregnancy without talking to your OB-GYN or allergist. Even “safe” drugs need to be chosen based on your health history, symptoms, and trimester.

Your provider will help you weigh: Is this symptom mild or severe? Can lifestyle changes help? Is there a safer alternative? What’s the real risk of not treating this?

There’s no one-size-fits-all answer. But there is a clear path: use the best-studied options, avoid the risky ones, and never suffer in silence.