Do Allergies Affect ADHD Treatment?

Jeff Copper

 Attention Magazine August 2019

 Download PDF

You may struggle with mental clarity if you have ADHD, but an allergy can affect your cognition even further. ADHD comprises many symptoms and often occurs with comorbid conditions, including seasonal or other allergies and sensitivities. Allergies can muddy our ability to think clearly whether we have ADHD or not. I’ve coached many individuals who experience such difficulties when their allergies act up. 

Charles Parker, DO, is a psychiatrist, bestselling author, neuroscience consultant, and an expert on brain science and medication. In one of my interviews with him on Attention Talk Radio (, Dr. Parker shared his insights on the effects of allergies, food sensitivities, and ADHD. 

According to Dr. Parker, allergies have different effects on each of us, depending on our own unique wiring. Our bodies have natural barriers that help to protect them from harmful foreign substances, and allergens attack those barriers, which in turn tax our body and brain. This can be very disruptive to an already taxed ADHD brain, often amplifying the ADHD symptoms. If not diagnosed accurately and quickly, a worsening of physical and mental awareness can impact our mental efficacy at work, school, and home. 

In addition, emotional regulation is often impacted negatively. As mental sharpness declines, individuals may look to antihistamines to improve their allergy symptoms—but the interaction between the antihistamine and the ADHD medication can have a substantially negative impact. In short, antihistamines interfere with the metabolism of the stimulant medication. As a result, cognitive performance may be below what the person experienced when their ADHD was untreated. Thus, when taken together, antihistamines and stimulants can make symptoms worse.

AllergiesIf you recognize negative side effects, it’s time to listen to your body. Mindfully listening to yourself is especially important if you have ADHD. If you notice your thinking isn’t as sharp as before, pause and take a step back. What is your brain telling you? You can’t write the business summary? You find preparing your tax return is daunting or even more daunting than ever before? Now, what could be the culprit? New medications? New schedule? Is the ragweed particularly bad? 

An allergic attack alone can change your mental sharpness, even without stimulant medication. If you notice side effects when taking ADHD medication along with allergy medications, it’s time to evaluate the variables. As Dr. Parker explains it, in order to have a positive effect, ADHD medications must pass through the body to get to the brain. This essential fact is often overlooked, yet it is critical. How a medication passes through the body is dependent on several factors, including the length of time a drug remains effective or its duration of effectiveness. Another important factor is the speed at which medication travels through each individual’s body. Medications that don’t reach the brain cannot produce the desired medical intervention.

It is important to remember that medication interactions can yield profound, negative consequences. Allergies and sensitivities can derail individuals with ADHD, Dr. Parker explains, and antihistamines can derail ADHD treatment. This could be why you notice that your ADHD medication isn’t working as well as it used to. If you aren’t paying attention to this, you can go down a confusing path.

 Be sure to research the characteristics of each medication you take to treat allergies as well as ADHD. Read Dr. Parker’s interview with William J. Walsh, MD, an international expert on measured impediments to medication effectiveness ( to learn more. Another important expert, Alessio Fasano, MD, chair of pediatric gastroenterology at Harvard University and founder of Massachusetts General Hospital’s Center for Celiac Research, has written a book on this topic. Called Gluten Freedom (Wiley, 2014), it documents the relevance of food sensitivities.

Do your own research and be your own advocate. Be aware if you experience an unpredictable side effect from allergy medications, especially antihistamines. We may try to ignore or forget about these interactions, but they are a very real threat and can directly interfere with your treatment. Discuss them with your doctor.

A certified ADHD coach based in Tampa, Florida, Jeff Copper, MBA, PCC, PCAC, ACG, CPCC, specializes in coaching adult individuals and entrepreneurs who have been diagnosed with ADHD later in life. He is a speaker, an attention expert, and host of Attention Talk Radio and Attention Talk Video. Learn more at