10 Surprising Signs You Have an Allergy or Sensitivity

Forget runny noses and itchy eyes — allergies can manifest in many unexpected ways.

Allergies, intolerances, and sensitivities don’t always turn up as a runny nose and itchy eyes. According to Leo Galland, MD, coauthor of The Allergy Solution, allergies are “great mimics” because they can manifest in unexpected ways. Many people may be suffering an allergy or sensitivity-related symptom and have no idea that an underlying immune reaction is the root cause.

These are some of the common symptoms of a sensitivity-related reaction or allergy that, on the surface, appear to be something else.

1. Weight gain

Allergies can lead to unexplained weight gain, or an inability to lose weight despite changes in diet and lifestyle. Studies have also linked antihistamine use with increased body weight.

2. Muscle aches

Sore muscles have been associated with some of the classic allergy manifestations, like asthma and eczema, and have been linked to certain food intolerances and reactions to specific metals, like nickel. Galland says many of his patients with a sensitivity to mold report muscle pain. 

3. Joint pain

Allergy-fueled arthritis, often triggered by problem foods, is one of the most common, well-established “hidden” allergies.

4. Fatigue

Feeling tired as a result of a sensitivity has been dubbed allergic tension—fatigue syndrome, and a food intolerance—often to wheat, corn, milk or chocolate — is likely the cause.

5. Brain fog

Galland says trouble with concentration and memory is often linked to food intolerances and mold sensitivity.

6. Bloating or stomachache

Food intolerances inflame the lining of the intestines, leading to cramping, bloating, and pain. A trigger food can also cause heartburn. An elimination diet may help root out the troublemakers.

7. Headaches

Decades of research have linked headaches — both migraines and nonmigraines — to allergies. Among the most common triggers are toxic fumes and foods like chocolate, nuts, soy, citrus, coffee, and alcohol.

8. Insomnia

A dairy intolerance may be the reason you’re having trouble falling asleep and staying asleep.

9. Hair loss

Alopecia areata is an autoimmune condition in which hair loss on the scalp goes beyond normal pattern baldness. It is more common among those who have been diagnosed with allergies, such as to gluten. Avoiding exposure may help stop — and even reverse — the hair loss.

10. Depression, mood disorders, or psychiatric symptoms 

A German study recently found that people with doctor-diagnosed allergies had higher rates of psychiatric symptoms. Galland notes that teenagers with asthma are about three times more likely than those without an allergy to be diagnosed with depression or a bipolar disorder later in life.