Why Allergy Symptom-Relievers Could be Harmful in the Long Run

When exposed to a harmful allergen, the body releases histamine — and that triggers allergy symptoms like itchy eyes and nose, runny nose, congestion, and more. When you take an antihistamine, it works to reduce the effect of histamine and therefore, the symptoms. That’s why antihistamines are usually the first line of defense when battling allergies.

These symptom-relieving medications are intended to be used as needed. For some patients, it’s the sole solution provided to tackle symptoms — and research shows that long-term use may be harmful in the long run.

Read on to learn the potential long-term side effects of extended antihistamine use, and how treating the cause of your allergies can help.


Side Effects of Antihistamines

There are two classes of antihistamines that may cause different side effects.

First Generation

First generation antihistamines include medications like Diphenhydramine, with brand names including Benadryl®. Though these can be used daily, they’re often used for more severe reactions, because of these common side effects:

  • Drowsiness
  • Headache
  • Dry mouth
  • Constipation
  • Nausea, vomiting
  • Hyperactivity, nervousness

Second Generation

Second generation antihistamines are more commonly used for daily use. Cetrizine, with the brand name Zyrtec®, and Fexofenadine, or Allergra®, can have side effects including:

  • Headache
  • Upset stomach
  • Drowsiness
  • Vomiting, diarrhea
  • Dizziness
  • Cough

Long-Term Effects

The side effects of both first- and second-generation antihistamines can be bothersome, but they typically go away once the antihistamine is out of the person’s system. Though research shows that they may also cause long-term effects when taken over an extended period — like long-term side effects, decreased effectiveness, and associated conditions.

Long-Term Side Effects

Some long-term side effects that patients have seen include drowsiness, dry eyes, mouth and sinuses, and stomach upset. These continue even after the patient stops taking the medication.

Decreased Effectiveness

With extended use of these medications, some find that the effectiveness decreases. This is due to tachyphylaxis — when the body builds a tolerance to antihistamines. Often, people bounce from one antihistamine to another once they stop being effective.

Associated Conditions

There are also studies that show long-term use might be tied to other conditions, like dementia. One study found that extended use of Diphenhydramine increased the risk of dementia in older adults because it blocks the effects of a neurotransmitter that is vital for memory. Out of 3,000 participants 65 years and older who took Diphenhydramine over a seven-year study, 54% developed dementia. Though this study doesn’t include a control group, other studies report similar results.


What To Do

If you’re taking antihistamines daily, you likely have a serious allergy, and you should consider treatment beyond symptom management. That means, getting to the root of what’s causing you to react and treating that, rather than masking with antihistamines.

Immunotherapy is the only disease-modifying treatment for allergies — and Allergychoices advocates for allergy drop immunotherapy. Following The La Crosse Method™ Protocol, allergy drops treat the specific allergens at the precise levels based on patient rest results. Over time, the doses gradually increase until the patient builds tolerance to the things that once made them sick.

Immunotherapy typically takes three to five years, but the lasting impact is positive — reduced or eliminated symptoms, reduced medication use, and increased quality of life. Find a provider near you that treats the cause of allergies here.