An ADHD dose that is too low usually looks like a medication that does not work. You take it, nothing happens, and the reasonable conclusion is that this drug is not for you.
That conclusion is often wrong, and it is wrong for a structural reason. ADHD stimulants are titrated rather than prescribed at a fixed dose, so the first amount you are given is a deliberately cautious floor, chosen to make side effects unlikely rather than to be the amount you need. [nice-ng87-dose] It is a starting point that is expected to move.
The clearest sign is nothing at all
If you notice no benefit and no side effects whatsoever, that is the strongest single indicator that the dose is below your range. A dose doing something usually announces itself somehow, even mildly: a slightly drier mouth, a smaller appetite at lunch, a difference in how the first hour of work feels.
Complete silence in both directions is unusual for a dose that is in the right region. It is the most common picture in the first week or two of treatment, and it is exactly when people decide the medication has failed.
Other underdosing signs are subtler:
- The benefit is real but very small, and you find yourself arguing with yourself about whether it is there.
- It helps on easy tasks and vanishes on the hard one you actually took it for.
- It works on a good day and does nothing on a bad one.
- Someone else notices a difference and you cannot.
Too little and too much look different
The two are often confused, usually because both get described as the medication not working. They are distinguishable, and being able to describe which one you are experiencing shortens the process considerably.
| Dose too low | Dose too high | |
|---|---|---|
| Attention | Unchanged, or briefly better | Locked onto the wrong thing for hours |
| Mood | As before | Flat, blunted, humourless, sometimes tearful |
| Body | Nothing noticeable | Racing heart, clenched jaw, tense, restless |
| Appetite | Normal | Gone, sometimes for the whole day |
| Sleep | Unchanged | Wired at bedtime, or waking early |
| Overall feeling | Nothing happened | Something happened and I do not like it |
The bottom row is the summary worth carrying into an appointment. Wanting more of it is a different report from wanting it to stop.
What the dose response actually looks like
Benefit does not rise indefinitely with dose. It climbs, plateaus, and then side effects begin to eat into the benefit, which is why the target is a band rather than a maximum.
A schematic of the titration pattern described in this article and in the guidelines cited. Not measured data, and individual ranges differ widely.
The useful dose sits where the two lines are furthest apart, and for most people that is nowhere near the top of the range. Pushing past it buys very little extra benefit and a lot of extra cost, which is the reason titration is done in steps with a review rather than in one jump.
Short duration is a different problem
A dose that clearly works and then stops by early afternoon is usually a timing problem, not a strength problem, and the two are fixed differently. Raising the morning dose to stretch the afternoon tends to produce more side effects in the morning while the afternoon stays much the same.
The fixes here are about formulation: a longer-acting release profile, a different preparation, or a small supplementary dose later in the day. Which of those applies depends on what you are taking, so the thing to bring to the appointment is the timing rather than a request for more.
Write down, for three or four days, when you took it, when you noticed it start, when it stopped, and what you were doing at each point. That record makes a far better case than a summary from memory, and memory is not what ADHD is best at.
When a higher dose is not the answer
Sometimes the dose goes up, the side effects arrive, and the benefit still does not. That result is informative rather than final.
A network meta-analysis of 133 randomised trials comparing ADHD medications found substantial differences between drugs in both how well they worked and how well they were tolerated. [cortese-2018-network-dose] A poor response to one is a poor response to one. Switching class, or switching within a class, is a normal next step rather than an admission of defeat, and the trade-offs are set out in our comparison of stimulant and non-stimulant options.
It is also worth asking what else is in the picture. Anxiety, sleep problems and mood conditions occur alongside adult ADHD often enough that they are the rule rather than the exception, and any of them can look like a medication that is not working. [katzman-2017-adhd-dose] Telling the two apart is covered in ADHD and anxiety. Treating the ADHD harder does not fix an untreated anxiety disorder sitting underneath it.
Take this to your prescriber, not to your pill box
Do not adjust the dose yourself, and do not double up on a bad morning. Stimulant titration is done deliberately and in steps for reasons that include your heart rate and your blood pressure, both of which are supposed to be checked as the dose changes. [nice-ng87-dose]
What helps is arriving with detail. Say which of the two pictures above matches yours, when the effect starts and stops, what changed for someone watching you, and what has not changed at all. Titration decisions turn on precisely that kind of specificity, and it is the first thing lost between the week you noticed it and the appointment six weeks later.
No screener on this site covers ADHD. The self-assessment tools here cover anxiety, depression, stress, insomnia, burnout, self-esteem and loneliness, and given how often those sit alongside ADHD, a result from one of them can be a useful thing to bring along.