The arrival of spring is traditionally associated with allergies, but the crisp air brought on by autumn’s cooler weather doesn’t necessarily mean everyone can take a breath of relief.

For many with allergies, fall is peak season that’s now probably compounded by a warming planet. Allergy season is starting earlier and lasting longer, which scientists attribute to a variety of causes, including the climate crisis.

As temperatures stay warmer for longer and the first frost gets delayed, plants that release allergens have more time to grow. What’s more, higher levels of carbon dioxide in the atmosphere due to fossil fuel use and emissions further drive plant growth, generating more pollen. More than 1 in 4 adults in the United States had seasonal allergies in 2021, according to the US Centers for Disease Control and Prevention.

It’s good to know common triggers for fall allergies and what symptoms people can expect. With respiratory viruses also prevalent in colder weather, how can people distinguish between seasonal allergies and a virus? What can be done to diagnose specific triggers, and how can people get relief from their symptoms?

To help us answer these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and adjunct associate professor at George Washington University, and she previously was Baltimore’s health commissioner.

CNN: What are common triggers for fall allergies?

Dr. Leana Wen: The most common culprit is a plant called ragweed. Ragweed grows wild just about everywhere in the United States. One plant can release 1 billion grains of pollen. Ragweed season typically begins in August and peaks in September but can last into November.

Other plants that can trigger fall allergies include burning bush, cocklebur, pigweed, sagebrush and tumbleweed. Molds can also cause seasonal allergies. In the fall, mold can accumulate in fallen leaves and bales of hay as well as indoors in damp places.

CNN: What symptoms should people expect?

Wen: Common symptoms include runny or stuffy nose, sniffling, sneezing, coughing, watery eyes, scratchy throat, and itching and burning in the nose, mouth and eyes.

CNN: With respiratory viruses also prevalent in colder weather, how can people distinguish between seasonal allergies and a virus?

Wen: There is no straightforward answer. Allergies tend to follow a seasonal pattern and get worse at certain times of the year. The symptoms persist for at least a week, usually longer. A lot of people experience the same symptoms year after year. Some symptoms that correlate more with allergies than colds are itchiness in the nose and throat and red and watery eyes.

Respiratory infections can also follow a seasonal pattern and are typically more common in the winter compared with the spring and fall, which are classic allergy season. One key distinguishing factor is the presence of a fever. Seasonal allergies don’t cause fevers. They also tend not to cause total-body symptoms like body aches and fatigue. And while people with allergies could develop a cough, the presence of a cough should make someone think of respiratory infections.

People who have had allergies before often know what works to treat them. Relief with allergy medications is a good sign that the symptoms are due to allergies. People can also take tests for various viral infections. There is no lab test for many cold viruses, but there is for flu, Covid-19 and RSV (respiratory syncytial virus). Some hospitalized patients can also receive a viral panel that includes a broader array of other respiratory viruses. The US government has just made another round of home Covid-19 tests available for free.
It’s a good idea to sign up for the free tests while we have the chance.

CNN: How can you diagnose specific allergy triggers?

Wen: Some people want to find out exactly what is triggering their allergies. They should contact their primary care provider for a referral to a specialist trained in allergy and immunology. That clinician can perform a skin prick test, where they put a small drop of different allergic triggers on your skin to see whether there is a reaction. They may also recommend a blood test looking for antibodies to the allergen.

CNN: What do we need to know about allergy triggers that could cause problems year-round?

Wen: Spring and fall tend to be peak allergy season because that’s when a lot of pollens get released, but there are other triggers as well. One to mention is dust mites, which are microscopic organisms that feed off of house dust and air moisture. They are a common type of indoor allergen and can cause year-round symptoms.

I have an allergy to dust mites and a very significant allergy to ragweed. So while I have some allergy symptoms year-round, they get especially bad in the fall.

Another category I want to highlight is food allergies. Nearly 6% of adults and children have food allergies, according to the US Centers for Disease Control and Prevention. These are different from seasonal allergies and can cause severe, even life-threatening reactions.

CNN: What treatments can help people get relief from their symptoms?

Wen: There are a variety of treatments that can help control seasonal allergies. To begin with, people should try to reduce exposure to the allergen. If the issue is ragweed, limit time outside when the pollen count is high, which is typically in the mornings through early afternoons.

Change clothes when coming indoors from outdoor activities. Keep windows and doors shut in the house and close the windows of the car while driving. Dry laundry indoors rather than hanging on a clothesline outdoors.

Medication can include antihistamine pills and nasal sprays to help with stuffiness. There are many over-the-counter options as well as some that are available by prescription only. People with severe symptoms may benefit from immunotherapy, also called allergy shots.

It’s always advisable to check with your physician or other healthcare provider before starting any new medication treatment. Some people respond well to over-the-counter options, while others may need a prescription medication or a combination of therapies.

Keep in mind that just because a medicine is available over the counter doesn’t necessarily mean there are fewer side effects. Diphenhydramine, an antihistamine, is sedating and can be very dangerous when taken in large quantities. And many nasal decongestants have interactions with other medications and are not meant to be used long-term.