5 Allergy Symptoms You Wouldn't Expect

Updated April 25, 2025

Some things in life are predictable: a sunburn after skipping the SPF, a sleepless night after staring at a screen before bed. But some issues — like seasonal allergies — don’t always play out in predictable ways. And while sneezing, itchy eyes, and a runny nose may be the hallmark symptoms you associate with allergies, they’re not always the symptoms you experience. In some cases, some unexpected health issues can arise when seasons change.

First thing’s first: what are seasonal allergies anyway, and why is spring seemingly the time of year when everyone is sniffling? An allergen is a tiny airborne particle like dust or pollen that provokes an immune response (aka an allergic reaction) in some people — these reactions can range from asthma to eczema and beyond, depending on the person. When we talk about “seasonal allergies,” we’re typically talking about allergies caused by outdoor allergens like tree pollen, grasses, or weeds that pop up in more plentiful numbers during certain months and in specific geographic locations.

Allergic reactions can vary significantly from person to person, but many people with seasonal allergies experience “allergic rhinitis,” also known as hay fever. This generally refers to a constellation of nasal symptoms, including stuffiness, itching, sneezing, and runny nose. According to the Asthma and Allergy Foundation of America, hay fever affects 19.2 million adults. But plenty of people who have seasonal allergies will experience something outside of the traditional hay fever symptoms. Here are five unexpected allergy symptoms to be aware of this season and beyond:

During an allergic reaction, your immune system produces histamines, chemicals that your body uses to try and fight the allergens. Histamines are your body’s way of being helpful in the presence of allergens, but while they’re intended to protect you, they can create some annoying side effects, like extra mucus production. This buildup of mucus, as well as general inflammation and swelling in the nasal passages can put pressure on your sinuses and result in a headache. If you’re experiencing regular bouts of pain localized over your sinuses or throbbing headaches that occur on one side, you may actually be experiencing seasonal allergies.

Even though we think of seasonal allergies as issues that primarily target the mouth, nose, and throat, they can also exacerbate existing skin issues like eczema. The overlap between eczema and nasal allergies might be more common than you think. Children born into families with a history of allergic diseases like asthma or hay fever are at an increased risk for developing eczema. There may be a variety of explanations behind this link, but in some cases, a person can develop a rash simply by being in direct skin contact with the same allergens that are triggering their nasal and other symptoms. If you’re experiencing itchiness, swollen bumps, dry, bumpy patches, or other unusual skin symptoms, seasonal allergies may be to blame.

There are plenty of reasons you might experience dark circles under your eyes (late nights, dehydration, and genetics can all play a role). But one somewhat surprising contributor is a seasonal allergy. Otherwise known as “allergic shiners,” these allergy-induced bluish-black circles are caused by blood pooling under the eyes as a result of nasal cavity swelling. If you notice a darker-than-normal hue under your eyes and you’re also experiencing more common symptoms like an itchy throat, sneezing, cough, or runny nose, you may very well have seasonal allergies.

Allergies can make you feel tired or make you feel like you're experiencing "brain fog". These symptoms are partly due to the histamine release, and also because allergies can interrupt your sleep. If your nose is blocked or you’re sneezing a lot at night, it can be hard to get good rest. Not sleeping well makes you even more tired and makes it harder to focus or remember things during the day. Additionally, antihistamine medication that some people take to help allergy symptoms can cause drowsiness.

You may not think of tooth pain as a typical symptom of seasonal allergies, but all the congestion that can occur with allergic rhinitis can actually lead to aching upper molars, throbbing, or cold sensitivity. Similar to a sinus infection, when congestion is concentrated in an area known as the maxillary sinuses (located below the cheeks and above the teeth), it can put pressure on the nerves of the upper teeth, resulting in pain. It can be hard to distinguish the tooth-related symptoms of seasonal allergies from a sinus infection, so if you’re having pain of any kind, check in with your primary care provider.