Caffeine & ADHD: The Potential Positive & Negative Effects, According To Experts

ADHD is estimated to affect 2.5% of adults1. And it's getting a lot of attention lately in regards to the unexpected ways it can affect women and adults in general. If you've been diagnosed, your doctor may have recommended a stimulant medication such as amphetamine dextroamphetamine or methylphenidate. These stimulants are some of the most commonly prescribed ADHD medications, which influence attention and behavior by boosting the availability of the neurotransmitters dopamine and norepinephrine in the brain. 

But caffeine is also a stimulant that influences neurotransmitters such as dopamine—which raises the question: Could ingesting caffeine in the form of coffee, tea, or any other source be a safe way to help alleviate ADHD symptoms, or would it just make things worse? And is combining caffeine with ADHD medication even OK, or is it potentially dangerous?

If you've ever consumed coffee or tea in the morning, you're probably quite familiar with the physical and mental lift that soon follows. That's because coffee is a central nervous system (CNS) stimulant that's been shown to help enhance focus and concentration, banish fatigue, improve memory, and boost overall mental functioning—at least temporarily. 

Caffeine predominantly does this by acting as an adenosine receptor antagonist. Caffeine is similar in structure to adenosine, a chemical that binds to receptors in the brain and subsequently slows down the activity of neurons that produce attention-boosting neurotransmitters like dopamine. This has the effect of making us sleepy and less able to maintain focus. But when we consume coffee, tea, or energy drinks, caffeine binds to these receptors instead, which minimizes the impact of adenosine and thereby curbs its effects by indirectly increasing dopamine release2. 

Many people with ADHD have been found to "self-medicate" with caffeine3. And because both caffeine and stimulant ADHD medications influence the brain's dopamine system (via slightly different mechanisms), some experts believe it's reasonable to experiment with caffeine as a way to help curb symptoms—although, there are crucial things to consider such as the dose, whether you take medication, and the severity of your ADHD.  

"Stimulant medications for ADHD work to increase the amount of the neurotransmitter dopamine in the brain by slowing down its reabsorption, thus promoting increased focus," says Uma Naidoo, M.D., a Harvard-trained nutritional psychiatrist and author of This Is Your Brain on Food. "Therefore, consuming stimulating substances like caffeine can have similar effects on those with ADHD. Modest amounts of caffeine have been shown to help improve focus, stimulate the mind, and clear brain fog. Individuals with ADHD benefit from this form of a 'brain boost' as it helps them to focus on completing each task at hand." 

Other experts agree that it may be effective, particularly if ADHD symptoms aren't too severe. "It can be an effective option for mild ADHD, especially if the person is not having negative side effects such as GI symptoms, cardiac symptoms, or sleep disruption," says Lidia Zylowska, M.D., a psychiatrist at the University of Minnesota Medical School and author of The Mindfulness Prescription for Adult ADHD.   

So, while it appears that there's real potential for using caffeine to alleviate certain ADHD symptoms, caffeine can affect individuals quite differently—so there's reason to proceed with caution, listen to your body, and consult your doctor if you plan to use caffeine as a tool to manage ADHD. 

Caffeine's potential for side effects has prompted research into its combined effects with L-theanine—an amino acid found in green and black teas, which is noted to contribute to these beverages' purported calming and soothing health benefits. "Much like caffeine, this amino acid is shown to alter brain chemistry in a way that increases focus and clears the mind for reduced feelings of stress and anxiety," says Naidoo.

"In practice, L-theanine can help with anxiety, so perhaps there is some modulation of caffeine's negative effects," says Zylowska. "But this finding has to be further studied, to say there's a real benefit to the combination."

Now, another big question is: How does all the information above change when a person is already taking (or plans to start taking) stimulant ADHD medication? The answer isn't super straightforward since the effects of stimulant medications and caffeine are highly unique to each individual, as are symptoms of ADHD.

But, because both are stimulants, we do know that combining caffeine and ADHD medications "can potentially put someone at risk for having more serious side effects such as cardiac overstimulation," says Zylowska. "However, some patients combine caffeine with medications and are able to tolerate it well—it often depends on the dose of each."

According to Zylowska, some people may space out caffeine and stimulant medication—for example, relying on a morning cup of espresso to get going and using their stimulant medication later in the day. "Many patients also spontaneously decrease the use of caffeine as they start stimulant medications," she says. "But if they don't, it is really important to monitor for the synergistic side effects." (This refers to the fact that caffeine and stimulant medications have a synergistic effect that increases the other's effectiveness, which could potentially increase problematic side effects.)

For a generally healthy person, consumption of up to 400 mg of caffeine per day is generally safe and tolerable. But this may need to be much lower depending on your personal tolerance and whether or not you are taking medication. (Check out this handy guide to caffeine levels in nine popular drinks.)

Caffeine is certainly not off the table if you have ADHD—and it may even offer some benefits, thanks to its actions as a CNS stimulant. While research is far from conclusive, some studies suggest that consuming low-to-moderate amounts of caffeine can boost focus and alleviate problematic ADHD symptoms like impulsive behavior—although not as effectively as medication. These effects of caffeine may be even more beneficial when it's consumed along with the calming amino acid L-theanine, although more research is needed.