How Bad Is It Really to Take Allergy Medicine Every Day?

If you deal with allergy symptoms year-round, you likely take antihistamines to help relieve your symptoms.

Antihistamines — also known as "H-1 receptor antagonists" or "H-1 blockers" — are medications that help with allergies by blocking histamine, a chemical released by your immune system when it encounters allergens like pollen or pet dander, per the Cleveland Clinic.

While these medications are great at getting symptoms like watery eyes and a runny nose under control, they are not without some risk.

This may leave you wondering if it's bad to take allergy medicine every day, especially if your allergies are chronic. The answer, though, will depend on the ‌kind‌ of antihistamine you take.

Here, allergists share the possible risks of long-term antihistamine use, the safest antihistamines to use daily and medication alternatives to relieve your symptoms.

All allergy meds that are H-1 blockers fit into one of two categories: first-generation and second-generation antihistamines.

First-generation antihistamines have been around since the 1930s, while second-generation antihistamines weren't approved by the FDA until the 1980s, per the Cleveland Clinic.

The biggest difference between the two? First-generation meds cause drowsiness (by interacting with histamine receptors in your brain and spinal cord), while second-generation meds do not, per the Cleveland Clinic.

Examples of first-generation antihistamines include the following, per the Cleveland Clinic:

• Brompheniramine (Children's Dimetapp Cold)
• Chlorpheniramine (Chlor-Trimeton)
• Clemastine (Dayhist)
• Cyproheptadine (Periactin)
• Dexchlorpheniramine Dimenhydrinate (Dramamine)
• Diphenhydramine (Benadryl)
• Doxylamine (Vicks NyQuil, Tylenol Cold and Cough Nighttime)
• Hydroxyzine (Vistaril)
• Phenindamine (Nolahist)

Some second-generation antihistamines include the following, per the Cleveland Clinic:

• Azelastine (Astelin)
• Loratadine (Claritin)
• Cetirizine (Zyrtec)
• Desloratadine (Clarinex)
• Fexofenadine (Allegra)

While allergy medicines are great at relieving symptoms, there are some possible side effects and risks to know — especially if you take them every day.

While not an antihistamine (or technically an allergy medicine, either), many people turn to nasal sprays like Afrin when their allergies cause blocked sinuses.

Afrin is a decongestant spray that shrinks swollen blood vessels in your nasal passages, per the National Library of Medicine. (It's also advertised to help treat congestion from colds and allergies.)

But if you use this type of spray too often, and then suddenly stop, you may get rebound congestion (or congestion that comes back worse than before).

This condition is called rhinitis medicamentosa, and it happens from using nasal decongestants for more than three days, according to Houston Methodist.

"The more you use the nasal spray, the worse your symptoms get," says Sandra Gawchik, DO, FCP, a Pennsylvania-based allergist and fellow of the American Academy of Allergy, Asthma and Immunology.

And while "regular antihistamines won't cause rebound congestion, they also don't treat stuffiness very well," says Asriani M. Chiu, MD, director of the asthma and allergy clinic at Children's Wisconsin.

To avoid rebound congestion, try to limit the amount of decongestant nasal spray you use, or talk to your doctor about how often to use them. Also try to avoid active ingredients like oxymetazoline (Afrin), which can create rebound congestion, according to Houston Methodist.

Instead, try sprays called nasal corticosteroids (like fluticasone or Flonase), which are safe to use every day, Dr. Chiu says.

Antihistamines can dry out your gastrointestinal tract, Dr. Chiu says. This drying effect has to do with the way the drugs block your cholinergic receptors (one of the main neurotransmitters in your nervous system), Dr. Gawchik says.

Dryness means less water in your gut, which can cause your bowels to get backed up (i.e., constipation). Constipation is more common with first-generation antihistamines and/or if you take a decongestant, Dr. Gawchik says.

The same drying effect that causes constipation could also lead to dryness in other parts of your body.

Indeed, some people may get a dry mouth, nose or throat when taking antihistamines on a regular basis. It can even cause vaginal dryness, Dr. Chiu says.

This is especially true for people already prone to dryness, Dr. Gawchik says. For example, people with Sjogren's syndrome — an autoimmune disease that causes dry eyes and mouth — are more prone to dryness from using allergy medicine daily, she says.

Other people prone to full-body dryness are adults over 65 and those in postmenopause, Dr. Gawchik adds.

During a particularly bad allergy season, you might be tempted to take more medicine than usual to manage your symptoms.

But whenever you take too much of a drug, there's always a possibility of harm, including a risk of overdose.

"If you take more than the standard dose, the risk of side effects increases," Dr. Gawchik says.

Taking double or triple your 'normal' dose may cause the following issues in some people, per Dr. Gawchik:

• Sedation
• Risk of falling
• Poor judgment, disorganized thinking, inability to perform regular tasks and other cognitive impairments
• Arrhythmia (irregular heartbeat)

While the likelihood of overdose is greater with first-generation antihistamines, there are still risks with the non-sedating, second-generation meds, too, Dr. Gawchik says.

The takeaway: Don't take extra medicine. As long as you stay at the standard dose, allergy medications are safe in most cases, Dr. Gawchik says.

Taking antihistamines long term may cause you to gain weight. One possible reason this may happen is because histamine can reduce your appetite. So taking an allergy med — which blocks histamine — could counteract this effect, according to the American Academy of Allergy, Asthma & Immunology.

In fact, one particular first-generation antihistamine called cyproheptadine is often prescribed to people to help stimulate their appetite, according to the Cleveland Clinic.

Some preliminary research has found that people who take antihistamines like cetirizine and hydroxyzine report increased feelings of depression (and anxiety), according to the Cleveland Clinic.

Still, more studies are needed to confirm whether there's a correlation between antihistamines and mood disorders. Evidence so far is purely anecdotal.

Your risk of getting dementia naturally increases as you age, especially if it runs in your family.

But there are a few studies that explore a possible connection between long-term anticholinergic drug use (including first-generation antihistamines) and an increased risk of dementia or cognitive decline.

One such example is a March 2015 study in ‌JAMA Internal Medicine,‌ where researchers followed more than 3,000 participants age 65 and older (without dementia at the start) for about 10 years.

Of the participants, those who took anticholinergic drugs long term — such as tricyclic antidepressants, first-generation antihistamines or bladder medications — were more likely to develop dementia than those who didn't. (Keep in mind, there are other factors that can contribute to developing dementia, too, like genetics or chronic illness.)

One possible explanation for this? Anticholinergic medicines like first-generation antihistamines block acetylcholine — a neurotransmitter that's important for learning and memory, per Harvard Health Publishing.

"Older adults — who naturally make less acetylcholine in the brain — are more susceptible to these cognitive effects," Dr. Gawchik says. This could also mean antihistamines may cause delirium in people who already have dementia, too.

That said, Dr. Gawchik warns that evidence around dementia and daily antihistamine use is still inconclusive. "There are many other factors that can contribute to these findings," she says.

For example, older adults already tend to develop more chronic diseases and take more medications, which can all play a role in developing dementia.

"Taking a first-generation antihistamine [on top of these predispositions] may just compound this decline," Dr. Gawchik says. "More studies are needed to confirm whether there's a concrete link between allergy drugs and dementia," she adds.

Both Dr. Gawchik and Dr. Chiu agree that second-generation, non-sedating antihistamines are the safest for long-term, daily use. These include the following:

• Cetirizine (Zyrtec)
• Fexofenadine (Allegra)
• Levocetirizine (Xyzal)
• Loratadine (Claritin)

When taken at standard doses, these meds tend to have fewer side effects and don't have the same effects on the brain and nervous system as older drugs like Benadryl do.

If you're in the group of people who shouldn't take antihistamines every day, or if you're simply trying to stay away from them, you can try these other options for managing your allergies.

Try to limit your exposure to allergens or irritants that may trigger your symptoms. Dr. Gawchik recommends the following strategies to avoid allergens:

• Use mattress covers if you have dust mite allergies
• Clean and dust your house daily
• Try to avoid wearing outdoor shoes inside your house
• Keep your windows closed to keep the pollen outside
• Use air conditioning instead of overhead fans, which can circulate dust and other allergens
• Shower and wash clothes after being outdoors to remove pollen
• Exercise first thing in the morning before the plants start to pollinate (prior to 10 a.m., the pollen count tends to be lower)
• See an allergist to get tested for allergens

Immunotherapy, aka allergy shots, works by gradually exposing you to an allergen, which causes your immune system to grow less sensitive to it over time, according to the American College of Allergy, Asthma, and Immunology (ACAAI).

Besides shots, there are also tablets that dissolve under your tongue (known as sublingual immunotherapy) and allergy drops (though they're not FDA-approved in the U.S.), Dr. Gawchik says.

Just keep in mind that immunotherapy takes time — the process can take up to three years — so this isn't a 'quick fix' to your allergy issues.

That said, the treatment works well in most cases, so it might be worth it long term. Allergy immunotherapy doesn't "cure" you, but it's very effective at lowering your allergic response to environmental allergens, Dr. Gawchik says.

"Saline nasal spray or irrigation is good, too, because it can 'flush away' allergens caught in your sinuses (like dust or pollen), and the saline can help decrease inflammation," Dr. Chiu says.

While helpful, saline sprays and rinses don't treat systemic symptoms, though (like headache, watery eyes or swelling), Dr. Gawchik says.

"Nasal steroid sprays are effective and safe, too," Dr. Chiu says. They're particularly good if you have congestion because antihistamines don't treat stuffiness, she says.

Nasal corticosteroids (like Flonase) decrease swelling and mucus in your nasal passages, according to Mount Sinai. Not only are they safe for daily use, but they offer the best results when used every day.

And because they only work in your nasal passageway, these sprays (when used as directed) don't usually affect other parts of your body. The most common side effects are dryness, burning or stinging in your nasal passage, sneezing or throat irritation, per Mount Sinai.

Cromolyn nasal spray (aka, Nasalcrom) is another alternative if you get allergy symptoms like sneezing, or an itchy, runny or stuffy nose, Dr. Gawchik says.

Cromolyn also reduces inflammation and substances in your body that release to cause allergy symptoms, according to the Cleveland Clinic. It's safe to use daily and has no sedating side effects, Dr. Gawchik says.

If you deal with allergies year-round, it's generally safe to take second-generation, non-sedating allergy medications like Claritin or Zyrtec every day (unless directed otherwise by your doctor).

First-generation antihistamines like Benadryl, however, can cause potential side effects if you take them daily (especially if you're an older adult or have an underlying health condition), so talk to your doctor before trying them out.

The bottom line? While most people are OK to take a daily second-generation allergy med, always talk to your doctor first. They can help you determine whether a daily allergy pill is right for you.