Is it normal for ADHD medication to change my child's appetite or mood?

If your child's eating or mood has changed since ADHD medication began, move beyond "Is this normal?" Ask what has changed, how urgent it is and who needs to know.

ADHD medication is not one medicine. Effects and instructions differ between medicines, formulations and children. Use the leaflet supplied with the prescription and the contact advice from the prescriber or pharmacist. This article helps you describe what you are seeing; it cannot tell you what is causing it or whether the medication should change.

What should I notice about appetite?

Loss of appetite is listed by the NHS as a common side effect of methylphenidate for children ^[3]. NICE recommends monitoring effectiveness and adverse effects throughout ADHD treatment and measuring children's growth on a defined schedule ^[1].

"Eating less" can mean several things. A child may leave lunch, feel sick, have stomach pain, drink less, avoid a particular texture or eat at a different time. Record the detail rather than deciding that appetite has disappeared.

For a few days, note:

• what the child says about hunger, taste, nausea or pain;
• what food and drink they manage, without turning every mouthful into a score;
• when the change appears and when eating is easier;
• whether clothes fit differently or the child seems physically unwell;
• the exact medicine, formulation and current instructions;
• any illness, stress, sleep change or other medicine that may be relevant.

Do not move the dose or change how the medicine is taken to fit a general eating suggestion. Some formulations have particular instructions about food and timing. Take the record to the clinician or pharmacist who can interpret it for your child's prescribed medicine.

How should I describe a mood change?

Words such as "moody", "flat" or "not themselves" are understandable, but they leave the prescriber guessing. Describe the observable change and include the child's own account.

For example:

Since Thursday, N has cried on four afternoons between 4.00 and 5.00 pm. Yesterday they said, "Everything feels too loud and I want to be alone." This began after the latest prescription change. School reports that N has also been quieter at lunch.

That note gives a time, frequency, source, recent change and the child's words. It does not assume that the medicine caused the change or label it as "rebound".

For methylphenidate, NHS advice lists changes in mood or personality, including aggression, irritability, depression, anxiety or tension, among serious effects for which families should call the child's doctor or NHS 111 straight away ^[3]. Other ADHD medicines have their own adverse-effect and urgency information.

Is a difficult late afternoon always rebound?

No. A late-day change may happen as a medicine's effect changes, but timing alone cannot establish the reason. Hunger, tiredness, pain, the end of the school day, travel, social effort, the environment and a recent medicine change can overlap.

Record both the difficult period and the rest of the day. Ask:

• What did the child experience earlier?
• What was different about food, sleep, school or travel?
• Does this happen on every day, only some days or also when the routine changes?
• What does the child think is happening?
• What benefit, if any, was noticed before the difficult period?

The prescriber can then consider the full pattern. Do not change the dose or timing to test a theory at home.

What belongs in the next review?

Bring a short comparison, not a verdict.

Ask the prescriber:

1. Which of these changes could be related to the medicine, and what else should be considered?
2. What should we continue to record?
3. Which symptoms should prompt contact before the next review?
4. Who should we contact and how?
5. What is the next review date?

NICE recommends that treatment reviews consider benefits, adverse effects, the child's or young person's preferences, effects across the day and the impact on education and other support needs ^[1].

When should I get help sooner?

Follow the instructions for the exact medicine. For methylphenidate, call the child's doctor or NHS 111 straight away for the serious effects listed by the NHS, including changes in mood or personality, palpitations, hallucinations or new facial tics ^[3].

Call 999 or go to A&E for the methylphenidate emergency symptoms listed by the NHS, including thoughts of self-harm, chest pain, seizures or signs of a serious allergic reaction ^[3]. If someone's life is at risk or you cannot keep them or somebody else safe, use emergency help rather than waiting for a medication review.

The understanding ADHD medication guide explains baseline checks, titration, monitoring, shared care and review questions in more detail.

Sources and further reading

1. [1] NICE. Attention deficit hyperactivity disorder: diagnosis and management. NG87 (accessed 3 August 2026).
2. [2] NHS. ADHD in children and young people (accessed 3 August 2026).
3. [3] NHS. Side effects of methylphenidate for children (accessed 3 August 2026).