Do Allergies Affect Blood Sugar? Seasonal allergies and blood sugar can feel like a frustrating combination, especially when symptoms and medications start to shift your blood sugar in ways you didn’t expect.
If you’re living with diabetes, seasonal allergies and blood sugar management go hand in hand more than most people realize. Blood sugar isn’t just influenced by food, it’s also impacted by stress, illness, inflammation, and even over-the-counter (OTC) medications. Allergy season brings all four into the picture, which is why you may notice changes even when your routine hasn’t changed. Understanding what’s happening in your body can help you stay one step ahead.
***This article is not intended to provide medical advice, diagnosis, opinion, treatment or services. This article and the links contained in it provide general information for educational purposes only. The information provided in this article is not a substitute for medical care, and should not be used in place of the advice of your physician or registered dietitian.
How seasonal allergies affect blood sugar
You might be asking yourself: do allergies affect blood sugar? And the answer is yes, just not in an obvious way.
When your body is exposed to allergens like pollen, it triggers an immune response that can lead to symptoms ranging from mild to severe. This response triggers inflammation which can lead to the release of hormones that may temporarily raise blood sugar levels. Just like other stressors, this can raise blood sugar by increasing the amount of glucose released from the liver and making your body less sensitive to insulin.
In other words, your body treats allergies similarly to illness or stress, which can impact blood sugar levels. You may notice higher fasting blood sugar levels, more fluctuations throughout the day, and less predictable responses to meals.
On top of that, allergy symptoms like poor sleep and fatigue can reduce physical activity. And since movement helps improve insulin sensitivity, less activity can further contribute to elevated blood sugars over time.
Allergy medications and their impact on blood sugar
Managing allergy symptoms is important, and a common way to do so is through OTC medications. However, there’s a clear connection between allergy medications and blood sugar, and understanding it can help you make more informed choices. Let’s dive deeper into some common OTC medications.
Antihistamines and blood sugar levels
Antihistamines are often the first thing we reach for during allergy season. These work by blocking histamine, a chemical in your body released during an allergic reaction. They reduce symptoms like sneezing, itching, and runny nose. Common OTC antihistamines include medications like Claritin (loratadine), Zyrtec (cetirizine), and Benadryl (diphenhydramine).
When it comes to antihistamines and blood sugar levels, most oral antihistamines have minimal direct impact on blood sugars. That means they’re generally considered safe for people with diabetes.
But “minimal” doesn’t mean “zero,” and there are still a few things to consider. Some antihistamines can cause drowsiness, which may reduce activity and cause less glucose uptake by muscles. Additionally, drowsiness may make it harder to recognize low blood sugar symptoms.
So while these medications don’t usually spike blood sugar directly, they can still influence your overall blood sugar patterns.
Benadryl and blood sugar levels
Let’s take a closer look at one of the most common OTC antihistamine medications, Benadryl.
There’s a lot of curiosity around diabetes, Benadryl, and blood sugar, mainly because it’s a first-generation antihistamine that tends to cause more noticeable side effects. First–generation antihistamines cross the blood-brain barrier, which often causes drowsiness.
Benadryl doesn’t typically raise blood sugar directly, but it can indirectly affect your numbers. Drowsiness can lead to lower activity levels, disrupted routines, and increased risk of missing early low blood sugar symptoms.
Because of this, many people with diabetes prefer to use non-drowsy options when possible, especially during the daytime.
Claritin vs Zyrtec for diabetes
If you’re deciding between options, you may be wondering about Claritin vs Zyrtec for diabetes.
The good news is that both are second-generation antihistamines and are generally considered safe choices. Unlike first-generation, second-generation antihistamines do not cross the blood-brain barrier, are more targeted, less sedating, and typically have fewer side effects. Let’s look at how the two compare.
Claritin (loratadine) and Zyrtec (cetirizine) are both antihistamines that help reduce common allergy symptoms. They work in similar ways to control allergies and are both available over the counter in similar forms.
Zyrtec has been shown to cause more drowsiness than Claritin, but Claritin has been shown to take longer to start working.
From a blood sugar perspective, neither one has a major advantage. The best choice comes down to how your body responds and which one controls your symptoms more effectively.
Decongestants: the biggest concern
If there’s one category of allergy medications to pay closer attention to, it’s decongestants. Decongestants narrow blood vessels in the nose, decrease swelling and relieve congestion and sinus pressure. Common OTC decongestants include Sudafed PE (phenylephrine) and nasal sprays such as Afrin (oxymetazoline).
Decongestants are also often found in combination products and include ingredients like pseudoephedrine and phenylephrine. If you see a “D” on the label (like “Claritin-D”), that’s your sign it contains a decongestant. Decongestants work by stimulating the nervous system, leading to the release of epinephrine and norepinephrine. This can raise blood sugar levels by prompting the liver to release stored glucose, while also decreasing insulin sensitivity, and reducing insulin secretion.
This is why decongestants are often considered the worst OTC allergy medicine option for people with diabetes. They can increase blood sugar levels, raise blood pressure, and temporarily worsen insulin resistance.
Don’t overlook hidden sugars
One factor that is often overlooked during allergy season is added sugar in medications.
Liquid syrups, chewables, and even lozenges may contain added sugars that can raise your blood sugar without you even realizing. While the amount per dose may seem small, it can add up if you’re using these medications multiple times per day.
When possible, choose sugar-free versions, opt for tablets instead of liquids, and check labels for added sugars.
Choosing the best allergy medicine for diabetes
So, what is the best allergy medicine for diabetes?
Instead of focusing on one “perfect” option, it’s more helpful to look at characteristics. Generally preferred characteristics include single-ingredient antihistamines, non-drowsy formulas, and tablets or capsules.
You should use caution with combination medications, products with decongestants, and liquid or chewable options with added sugars as these may impact your blood sugar.
For many people, managing seasonal allergies and blood sugar comes down to choosing medications that minimize blood sugar fluctuations on the body while still effectively controlling symptoms.
Remember, blood sugar management involves many different factors, what works best for one person may not work the same for another.
Practical tips for managing blood sugar during allergy season
Managing seasonal allergies and blood sugar doesn’t have to be complicated. Here are a few simple tips to help you stay on track:
- Monitor blood sugars more frequently: Especially when symptoms are severe or medications change
- Stick to consistent meals: Balanced meals with protein, fat, and fiber can help stabilize blood sugar
- Stay active when possible: Even light movement can improve insulin sensitivity. Exercising indoors can minimize exposure to pollen and other allergens
- Pay attention to patterns: Your body will tell you what’s working (and what’s not)
- Loop in your healthcare team: If you notice consistent changes, they can help adjust your plan
Small, consistent habits can make a big difference when navigating seasonal allergies and blood sugar throughout the year.
OTC Allergy Meds for Diabetes Download
Download my easy guide (with photos) for OTC allergy meds for diabetes!
Conclusion: Do Allergies Affect Blood Sugar?
At the end of the day, seasonal allergies and blood sugar are more connected than they first seem. Between your body’s immune response and the medications used to manage symptoms, there are multiple factors that can influence your blood sugar levels.
The goal isn’t to avoid treating your allergies, it’s to treat them strategically. With a little awareness and some thoughtful choices, you can manage your symptoms and keep your blood sugar steady at the same time.
