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A flare up of allergy symptoms can happen any time of year. In fact, about two-thirds of people who have seasonal allergy, actually have allergy symptoms all year, although they may not be as obvious. Symptoms like cough and congestion may be caused by winter or indoor allergies like pets, mold, or dust. [1,2]
Seasonal allergy can start when trees start to pollinate. Tree pollen allergies can start as early as February. Grass pollen starts next in early spring. If you live in a tropical climate, grass pollens may be around most of the year. A rainy April or May can cause mold pollens to last into the fall. Weed pollens, especially ragweed, kick in from August through November. 
What Causes Allergy Fatigue?
According to the American College of Allergy, Asthma & Immunology (ACAAI), although you might not think about fatigue or sleepiness as allergy symptoms, untreated allergies often lead to these symptoms. One reason is that an allergic reaction can release chemicals in your body that directly cause fatigue. 
A more obvious cause is lack of sleep. When you can’t breathe well through your nose or you are coughing and sneezing all night, it’s hard to get a good night’s sleep. Finally, if you are not careful about your over-the-counter (OTC) allergy medications, they may cause drowsiness or disrupt your sleep. 
Do Antihistamines Make You Sleepy?
It depends on the type. Allergy symptoms are caused by your body’s defense system, called the immune system. If you have allergies, your immune system identifies otherwise harmless substances like mold spores or tree pollens as foreign invaders, and launces an attack against them. One of the main chemicals released is histamine. It causes allergic rhinitis and itchy, watery eyes. To treat your seasonal allergy symptoms, you may opt for over the counter medication found in the allergy section of your pharmacy. These are OTC antihistamines, and are effective for some seasonal allergy sufferers because they block the effects of histamine. 
There are two types of OTC antihistamines. Older antihistamines, called first-generation antihistamines cause drowsiness along with dry eyes and constipation. Common brand names are Benadryl and Chlor Trimeton. Both the FDA and ACAAI suggest avoiding these antihistamines. 
The best bet is to ask your doctor to recommend an OTC allergy medication or to choose a newer non-sedating OTC antihistamine. Non-sedating means it won’t make you sleepy. There are several OTC non-drowsy antihistamine brands, such as Zyrtec, Claritin, and Allegra. Look for non-sedating on the label or ask your pharmacist. 
Other Non-Drowsy Allergy Medicines
In addition to non-sedating antihistamines, there are other OTC options to treat your allergies. These include: [3,4]
- Intranasal corticosteroids. These are nasal sprays that block immune system swelling and irritation (inflammation). These nasal sprays block persistent nasal allergy symptoms. Several are available OTC, and others by prescription.
- Decongestant nasal sprays. These sprays give immediate results for nasal congestion by shrinking your nasal tissues. The problem is that they have a rebound effect, your nasal tissues may swell up even worse when the medication wears of. These sprays should only be used for a few days at most to relieve nasal congestion.
- Pseudoephedrine (Sudafed). This medication is an oral decongestant that opens up your nasal passages, but it has significant side effects including loss of appetite, palpitations, and insomnia. Although it is a stimulant – it is the main ingredient of methamphetamine – it can cause sleepiness indirectly by interfering with your sleep schedule. Because of these side effects, you need to ask a pharmacist for pseudoephedrine. It is kept off the pharmacy shelves.
How to Tell the Difference Between COVID and Seasonal Allergies?
For more information on COVID 19, head to the University Health News Coronavirus Center.
COVID 19 and seasonal allergies have different causes, but share a lot of the same symptoms. It is important to know the difference. You can try to treat your seasonal allergies with OTC meds, but with COVID 19 symptoms you will need a call to your doctor. 
- Symptoms that can occur in both COVID 19 and seasonal allergy are cough, fatigue, sneezing, sore throat, runny nose, red eyes, and loss of smell or taste.
- Symptoms of seasonal allergy that are not seen in COVID 19 are itchy nose or eyes.
- Symptoms of COVID 19 that are not seen in seasonal allergy are fever, muscle aches, nausea, vomiting, or diarrhea.
- COVID 19 can cause difficulty breathing. Seasonal allergies do not cause difficulty breathing or shortness of breath unless you also have asthma, and your allergies trigger an asthma attack.
Final Tips for Managing Seasonal Allergy Fatigue and Other Symptoms
If you are struggling to control allergy symptoms on your own, see your health care provider. You may want to see an allergy specialist. You can be tested to find out which allergies you have, which can help you avoid them. Avoidance is often the best treatment. Your doctor may prescribe effective allergy medications that are not available OTC, including an antihistamine nasal spray or allergy shots, called immunotherapy. Other management tips include: [2,3]
- Check weather reports for pollen levels. Avoid outdoor activities on high pollen days.
- Keep your house and car windows shut and turn on air conditioning during allergy season.
- Take a shower and change your clothes after coming home during allergy season.
- Wear a mask when outdoors, especially when mowing the lawn or raking the leaves.
- Remember that spring and summer pollen levels are highest in the evening and fall pollen levels are highest in the morning. All pollens are higher on dry and windy days.
 ACAAI, Fatigue | ACAAI Public Website