Written by Alexa Mader, PharmD | Reviewed by Stacia Woodcock, PharmD Published on January 19, 2023
Key takeaways:
- Antihistamines like diphenhydramine (Benadryl) and cetirizine (Zyrtec) aren’t known to raise blood pressure when used alone.
- Antihistamines are part of many combination over-the-counter (OTC) cough and cold products. They may be combined with a medication that can raise your blood pressure. This includes ibuprofen (Advil, Motrin) or pseudoephedrine (Sudafed).
- If you have high blood pressure, talk to your healthcare provider and pharmacist before taking an OTC cough and cold product. They can help you make sure you are avoiding products that may raise your blood pressure.
Credit: urbazon/E+ via Getty Images
Antihistamines are a broad group of medications. They treat symptoms of common medical conditions like allergies and the common cold. Many common antihistamines — like diphenhydramine (Benadryl) and cetirizine (Zyrtec) — are found over the counter (OTC).
Antihistamines are widely used. But, they may not be the best option for everyone. For example, it’s a good idea to avoid Benadryl in people who are over 65 years old. It can cause excessive drowsiness and confusion which makes falls and injury more likely.
If you’re someone who takes antihistamines, you may wonder if they can cause high blood pressure. After all, many OTC and prescription medications can have this effect. But are antihistamines one of them?
What are antihistamines?
Antihistamines are a group of medications that treat many medication conditions. This includes seasonal allergies, trouble sleeping (insomnia), and common cold symptoms. Many of them are found OTC.
Antihistamines work by blocking the histamine receptor. This stops histamine from having its usual effects. Histamine is a natural chemical that’s released when your body is triggered by an allergen or irritant. The release of histamine creates symptoms like a runny nose, itchy eyes, and sneezing.
Antihistamines can be divided into two groups: first-generation and second-generation antihistamines. First-generation antihistamines work quickly to relieve allergies and common cold symptoms. But one of their most common side effects is drowsiness. For this reason, they’re sometimes also used to help people sleep.
Examples include:
- Diphenhydramine (Benadryl)
- Doxylamine (Unisom SleepTabs)
- Chlorpheniramine (Aller-chlor)
- Hydroxyzine (Atarax, Vistaril)
Second-generation antihistamines also work to relieve allergy symptoms. But they tend to have less side effects. They also last longer in the body and may only need to be taken once a day. Examples include:
- Cetirizine (Zyrtec)
- Loratadine (Claritin)
- Desloratadine (Clarinex)
- Fexofenadine (Allegra)
Do antihistamines increase blood pressure?
The oral antihistamines discussed above aren’t known to raise blood pressure. Other forms of antihistamines are also considered safe. This includes azelastine nasal spray (Astepro) and eye drops and olopatadine eye drops (Pataday products).
But oral antihistamines are often part of OTC combination cough and cold products. And other ingredients in these products may raise your blood pressure. This includes pain relievers like acetaminophen (Tylenol) and ibuprofen (Advil, Motrin). And oral decongestants like pseudoephedrine (Sudafed) can also have this effect.
Examples of combination products that contain these medications include:
- Allegra-D (fexofenadine / pseudoephedrine)
- Zyrtec-D (cetirizine / pseudoephedrine)
- Claritin D (loratadine / pseudoephedrine)
- Advil Allergy and Congestion Relief (chlorpheniramine / ibuprofen / phenylephrine)
- Tylenol Cold + Flu + Cough Night (acetaminophen / dextromethorphan / doxylamine / phenylephrine)
These products are also available under many other names. So make sure you read the medication label carefully when buying an OTC medication. If you’re still not sure, ask your pharmacist. They can help you understand what ingredients are part of any OTC product.
Keep in mind: If you don’t have high blood pressure, using these OTC products probably won’t cause blood pressure problems. But if you already have high blood pressure, you may need to be more careful. Talk to your healthcare provider before trying OTC products in this case.
How much will my blood pressure increase after taking antihistamines?
It’s unlikely that you’ll see an increase in your blood pressure when taking antihistamines. But as mentioned, combination products with ibuprofen, acetaminophen, or decongestants may raise blood pressure.
These medications may affect everyone differently. But acetaminophen and ibuprofen have been found to increase blood pressure by up to 5 mmHg (mmHg is the unit of measurement by which blood pressure is measured). Pseudoephedrine has been found to raise blood pressure by up to 2 mmHg.
What side effects are common with antihistamines?
First-generation antihistamines generally cause more side effects than second-generation antihistamines. Some common side effects seen with first-generation antihistamines include:
- Sleepiness
- Dizziness
- Constipation
- Trouble with coordination
- Dry mouth
- Dry eyes
- Urinary problems (like trouble peeing)
These side effects may be possible with second-generation antihistamine too, but they’re much less common.
The bottom line
Antihistamines like Benadryl help relieve symptoms of various medical conditions like allergies and the common cold. When used alone, they aren’t known to cause high blood pressure. But they’re often combined with other medications that can raise your blood pressure. This includes ibuprofen, acetaminophen, and decongestants like pseudoephedrine.
So if you have high blood pressure, make sure to talk to your healthcare provider or pharmacist about what OTC combination products are safe.
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