When to call the doctor about ADHD medication side effects

4 min read · Last reviewed Wed Jul 08 2026 00:00:00 GMT+0000 (Coordinated Universal Time)

Common, usually manageable side effects

Most children tolerate ADHD medication well, but these effects are common enough that they're worth knowing about in advance rather than being alarmed by them:

Reduced appetite, especially around midday
Difficulty falling asleep if the dose is too late in the day
Mild headache or stomach ache in the first week or two
A temporary "flat" or quiet mood as the body adjusts
Slight increase in heart rate or blood pressure (monitored at review appointments)

These often settle within the first few weeks, or can be improved with small adjustments to timing or dose — worth mentioning at a routine follow-up rather than necessarily an emergency.

Call your prescriber promptly (same day) if you notice

Appetite loss severe enough to affect daily functioning or that isn't easing after a few weeks
New or worsening tics
Significant mood changes — increased irritability, tearfulness, or signs of low mood
Sleep problems that persist despite timing adjustments
Any rash

Seek urgent medical attention if your child has

Chest pain, fainting, or a racing/irregular heartbeat
Signs of an allergic reaction (swelling of face/lips/throat, difficulty breathing)
Thoughts of self-harm, or a sudden and significant change in mood or behaviour
Hallucinations or unusual, out-of-character thoughts

If any of these occur, treat it as an emergency — call 999 (or your local emergency number) or go to A&E, and inform the prescriber as soon as possible afterwards.

Keeping track

A simple log — date, dose, what you noticed, how long it lasted — makes review appointments far more useful, since prescribers often adjust treatment based on patterns over weeks, not a single day's experience.

When to talk to your clinician