Do ADHD Meds Cause Tolerance?

Tolerance doesn’t develop for their cognitive benefits, but it may for other effects

STUDY: Smith C et al, CNS Drugs 2026;40:549–563

STUDY TYPE: Systematic review

FUNDING: National Institute for Health and Care Research (NIHR)

Background

Patients — and clinicians — frequently worry that ADHD medications stop working over time, a phenomena called tolerance or tachyphylaxis. This is the first systematic review to look at the evidence.

The Study

Seventeen studies were identified with durations ranging from days to ten years in duration, included children and adults, and covering methylphenidate, amphetamines, and clonidine. Most were small and methodologically limited; 12 of 17 were rated poor quality.

There was preliminary evidence for tachyphylaxis — meaning within-day fading of effect — to the mood and behavioral effects of stimulants. Short-term studies found tolerance to the subjective, euphoric effects of amphetamine in neurotypical volunteers (drug liking, excitation), but not to performance on cognitive tasks.

Longer-term studies in children with ADHD — including one following 108 children for 3–10 years — found no clinically meaningful tolerance to therapeutic effects. Only 2.7% of participants lost a previously good response without a clear explanation.

Unfortunately, there was no tolerance to their cardiovascular side effects, which persisted throughout treatment in virtually every study.

Practice Implications

1. Surprisingly, stimulants do not treat depression. They failed in all four large, industry sponsored trials, and this analysis in ADHD adds weight to that evidence.
2. When people take stimulants to treat ADHD, they feel calmer; more patient. The benefits are cognitive — more organized, focused, and better able to prioritize. Those benefits last. If they don’t, look for lifestyle changes that might be impeding them, like sleep deprivation, lack of exercise, or task overload.
3. If the stimulants don’t have cognitive benefits, but just boost energy, confidence, or mood, the effects are not likely to last. Taper off; don’t cause more tolerance by raising the dose.