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Attention Deficit Hyperactivity Disorder

Changing Dosages of Ritalin

01/11/2000

Question:

I have heard it said that a person who takes Ritalin must continue to increase the dosage over time as the body becomes sort of immune and requires more to be effective. Is this true if so how high can the dosages be expected to go? My son is 14 and on school days he takes three doses of Ritalin. 20mg 7am, 20mg 11am, 10mg 2pm.

Answer:

Your question is a very good one. In medical terms, you are asking if "tolerance" develops. The term "tolerance" is used to describe the effect noted when a person needs more and more of a drug to achieve the desired effect. The term does not include needing more or less of a drug because of unrelated physical changes such as aging, weight change, loss of liver function, and so on. A good example of tolerance is the one seen when someone drinks alcohol on a regular basis. They soon will need more and more to achieve the same "buzz" or "relaxation" or "numbing" effects. Thus, if they continue to drink to achieve their desired effect daily, they will soon need so much that it is bad for their mental and physical health, where a small amount might have been no problem. Thus, whether or not humans develop tolerance to stimulants is a key question. When someone becomes tolerant to a dosage of a medicine, but continues to take it (in increasing doses) to receive the original effect, it is a strong indicator of addiction. Especially when there are known health hazards. Thankfully, tolerance is NOT seen for stimulants such as Ritalin regarding the positive neurotransmitter effects that help with ADD/ADHD. Additionally, tolerance IS usually seen to other stimulant effects such as lack of appetite and decreased sleep. There is currently little good data on Ritalin dose changes needed over time in the scientific literature. In The Affinity Center, the center for adults and children with ADD where I have worked for three years, we have noticed two clear patterns. First, as with many medications, children usually need higher and higher doses as they age. This may be a function of wieght, liver changes, neurologic development, or something yet unidentified. Second, it is rare for an adult to need to increase dosage once his/her most-appropriate dose has been established. By far, the great majority of adults I have seen for greater than even two years are still at the same dose. A long answer to a fairly short question, but I hope it helps.

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Response by:

Susan Louisa Montauk, MD
Formerly Professor of Family Medicine
University of Cincinnati