Why Are Antihistamines Not Working for Me? Causes and Relief


Why do antihistamines stop working?

Antihistamines can stop working because your allergies might be getting worse or you might have immune system changes due to aging. You also might not be taking the medication as directed. If you take an antihistamine after being exposed to an allergy trigger, it won’t work as well.

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Allergy meds not working?

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When you suffer from allergies, antihistamines are often the first defense against itchy, watery eyes and a runny nose. Yet sometimes, they stop working. Many medications cause drug resistance and tolerance, which cause the body to stop responding well to the medication. But that’s not quite the case with antihistamines. When these allergy medications stop working, it’s often more complicated to figure out why.

How Do Antihistamines Work?

When your body is exposed to an allergen, it causes your immune system to start an immune response. During this response, the body releases a chemical called histamine. Histamine’s role is to rid your body of the allergen by triggering inflammation, producing mucus, and irritating the eyes, nose, and skin.

Antihistamines work by stopping the body from releasing histamine. And with no (or reduced) histamine, most patients experience fewer allergy symptoms.

Why Do Antihistamines Stop Working?

In some patients, antihistamines stop working after months or even years of use. Sadly, the people who most experience the most reduced benefit often suffer from chronic and severe allergy symptoms.

There are various reasons antihistamines may stop working. Here are some of the most common:

New or Worsening Allergies

One reason antihistamines quit working may be because you have new allergies or your allergies have gotten worse. In people with multiple allergy triggers, the immune response may strengthen over time, making your allergy symptoms worsen. And the worse your allergies are, the less effective antihistamines become.

Climate Change

Another reason your allergy medication quit working may result from climate change. With warmer weather, growing seasons have lengthened, and the pollen season now lasts longer than before. Heavy pollution, drought, and other climate-related issues can exacerbate allergies.

Immune System Changes

As you age, your immune system changes. It may not function as well or be as strong as it once was and, therefore, it reacts in different ways. Sometimes, this change manifests in not responding to certain medications, including antihistamines.

Not Taking Medication as Directed

While you can take antihistamines anytime you have an allergic reaction, to be most effective, take the medication daily during peak allergy season. In many cases, antihistamines work better when you take them before the allergic reaction begins and continue throughout the duration of exposure. If you stop the medication because allergy symptoms go away, symptoms can be hard to get under control.


Long-term stress disrupts your immune system and worsens allergies by increasing sensitivity to allergens and strengthening your immune response. When your stress levels increase, antihistamines may have a weakened effect and provide less relief than in less stressed periods.

Non-Allergic Reaction

You may experience what appears to be allergy symptoms but is actually a non-allergic reaction. Because the immune system isn’t releasing histamines, antihistamines don’t work. Things that cause non-allergic reactions include:

  • Pollution
  • Cleaning supplies
  • Smoke
  • Perfumes and cologne
  • Artificial scents
  • Viruses

If you have allergy-like symptoms but don’t find relief from antihistamines, pay attention to other things in your environment that could be the culprit.

What to Do When Antihistamines Stop Working?

If antihistamines did work for you but stopped for some reason, there are things you can do to address your symptoms. Limiting exposure, trying out a different medication, or using sublingual immunotherapy can help.

Limit Exposure

Reducing exposure to allergens can also help you manage your allergies. Avoiding peak pollen times, wearing a mask, and eliminating dust-harboring areas in your home like carpets, drapes, and upholstered furniture can also reduce your allergy symptoms.

  • Check pollen count: When the pollen count is high, try to stay indoors or wear a dust mask when leaving the house. You can find the pollen count on an app or local weather website.
  • Try an N95 mask: If you have to go outdoors on high pollen days, an N95 mask, sunglasses, and hat can help keep pollen off your face and out of your airways.
  • Shower when you get home: Pollen is going to stick to your hair and skin, so showering when you get home can help you wash it off and make sure you’re not bringing too much pollen into your home.
  • Take shoes off: When you get home, it’s a good idea to take your shoes off so you don’t track pollen in.
  • Clean your house often: During allergy season, you may want to clean your home more than you usually do. Vacuuming with a HEPA filter, dusting, and doing laundry more often are all good ways to keep allergen levels down in your home.

Alternative Medications

For those who experience different allergy symptoms now than in the past, changing antihistamines may help. In other cases, adding a nasal rinse or spray may help with sinus-related symptoms that aren’t responding to antihistamines.

  • Nasal sprays: Nasal sprays are specifically designed to target runny and stuffy noses caused by allergic rhinitis. They reduce inflammation in the nasal cavity to temporarily diminish swelling and congestion.
  • Eye drops: Eye drops can be used to help with itchy and watery eyes that are common among allergy sufferers.
  • Prescriptions: If OTC allergy medications fail to relieve your allergy symptoms adequately, you may need to see a doctor for a prescription-strength medication.

While these other medications might help relieve some of your symptoms, they aren't long-term solutions and can have some side effects. 

Over-The-Counter Allergy Medication Comparison Chart

Sublingual Immunotherapy

When allergies impact how you function and don’t respond to antihistamines, consider sublingual immunotherapy. Sublingual immunotherapy involves exposing your immune system to small doses of what you are allergic to in the form of allergy drops or allergy tablets.

By repeatedly exposing your immune system to small doses of your allergens, immunotherapy retrains your body to stop reacting to your allergies when exposed. This results in long-term relief from your allergies.

Take Our Allergy Assessment

If antihistamines no longer offer you the allergy relief you want, allergy immunotherapy may. At Wyndly, our allergy doctors will work with you to create a personalized allergy treatment plan for you to get you lifelong relief.

Take our two-minute assessment to see if you’re a candidate and start your journey to an allergy-free life today!

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