If you have ADHD, you may notice that certain medications seem to make your concentration, memory, energy levels or executive functioning worse.

This does not necessarily mean that the medication is making ADHD itself worse. Some medicines can cause side effects such as sedation, fatigue, cognitive slowing or sleep disruption, which can overlap with ADHD symptoms and make everyday functioning more difficult.

Other medications and substances may interact with ADHD treatments, particularly stimulants such as methylphenidate or lisdexamfetamine.

Understanding these effects can be helpful when reviewing treatment with your doctor.


1. Benzodiazepines

Benzodiazepines such as diazepam, lorazepam and alprazolam are sometimes prescribed for anxiety, acute agitation or insomnia.

Because they reduce activity within the central nervous system, they can cause:

  • drowsiness
  • slower processing speed
  • difficulties with attention
  • problems with memory
  • reduced mental alertness

For someone who already struggles with attention or working memory because of ADHD, these effects may be particularly noticeable.

Benzodiazepines can also lead to tolerance and physical dependence when used regularly, which is one of the reasons they are generally used cautiously, particularly for longer-term treatment.

This does not mean that someone with ADHD should never take a benzodiazepine. There may be situations in which they are clinically appropriate, but the potential cognitive effects should be considered.


2. Antihistamines

Not all antihistamines are the same.

Older, first-generation antihistamines such as diphenhydramine are more likely to enter the brain and cause sedation.

They can contribute to:

  • daytime sleepiness
  • reduced alertness
  • slower thinking
  • difficulty concentrating
  • “brain fog”

Newer antihistamines, such as loratadine, are generally much less sedating. However, individual responses vary, and even some newer antihistamines — particularly cetirizine — can cause drowsiness in some people.

If your concentration suddenly seems worse during allergy season, it is therefore worth considering not only the allergies themselves but also the medication being used to treat them.


3. Antipsychotic medications

Antipsychotics such as risperidone, olanzapine and quetiapine are prescribed for a variety of psychiatric conditions and, in some circumstances, for severe behavioural or mood symptoms.

Depending on the medication and dose, they may cause sedation, fatigue or cognitive slowing.

For a person with ADHD, this can sometimes feel like:

  • poorer concentration
  • reduced motivation or initiation
  • slower thinking
  • greater difficulty getting started with tasks
  • daytime tiredness

However, antipsychotics are often prescribed for important clinical reasons. If they are needed to treat another condition, the appropriate approach is not simply to stop them, but to discuss side effects, dose and treatment options with the prescribing clinician.


4. Sleep medications

Poor sleep can significantly worsen attention, emotional regulation and executive functioning in ADHD.

Ironically, some medications used to improve sleep can also cause residual daytime sedation.

For example, zolpidem may cause next-day drowsiness or reduced alertness in some people. Sedating medications sometimes used for sleep, such as trazodone, may have similar effects, particularly when treatment is first started or the dose is changed.

The aim of treating insomnia should therefore be not only to increase the number of hours slept, but also to improve daytime functioning.

If you are sleeping for longer but feel cognitively slower the following day, this is worth discussing with your doctor.


5. Some medications for blood pressure

Certain blood-pressure medications, including some beta-blockers, can cause fatigue or reduced energy in some people.

This does not mean that beta-blockers worsen ADHD directly. However, fatigue and reduced physical or mental energy can make executive-function difficulties more noticeable.

There is also an important distinction here: some medications that lower blood pressure are actually used in the treatment of ADHD.

For example, guanfacine and clonidine are non-stimulant medications that act on alpha-2 adrenergic receptors and may improve ADHD symptoms in appropriate patients.

Therefore, blood-pressure-lowering medication should not be considered one single category when discussing ADHD.


6. Asthma medication and ADHD stimulants

Asthma medications do not generally worsen ADHD symptoms directly.

However, some bronchodilators, particularly beta-2 agonists such as salbutamol, can cause:

  • increased heart rate
  • palpitations
  • tremor
  • feelings of jitteriness

Stimulant ADHD medications can also increase heart rate and blood pressure slightly in some people.

When these medications are used together, some individuals may therefore notice more palpitations, tremor or physical restlessness.

Having ADHD or taking stimulant medication does not mean that you should avoid necessary asthma treatment. Poorly controlled asthma carries its own risks and should be treated appropriately.

If you regularly need asthma medication and are also taking stimulants, your doctor can review your symptoms, blood pressure, pulse and overall asthma control.


ADHD rarely exists in isolation

ADHD commonly co-occurs with other neurodevelopmental and mental health conditions, including autism, anxiety disorders, depression, sleep disorders and substance-use problems.

This can make medication management more complex.

A medication that appears to make concentration worse may actually be treating another important symptom while causing sedation. Alternatively, worsening attention may be related to anxiety, depression, poor sleep, hormonal changes, physical illness or burnout rather than medication itself.

This is why treatment should be individualised rather than based solely on a list of medications that are considered “good” or “bad” for ADHD.

If your ADHD symptoms seem worse after starting a new medication, changing the dose or adding another treatment, it is worth reviewing this with your doctor.

Most importantly, do not stop prescribed medication suddenly without discussing it with the clinician responsible for your treatment.

The information provided is for educational purposes only and is not a substitute for an individual medical assessment.

Thank you for reading!


References :

National Institute for Health and Care Excellence. (2018, updated 2019). Attention deficit hyperactivity disorder: Diagnosis and management (NICE Guideline NG87).

National Institute for Health and Care Excellence. (n.d.). Methylphenidate hydrochloride: BNF. British National Formulary.

National Institute for Health and Care Excellence. (n.d.). Attention deficit hyperactivity disorder: Methylphenidate—Prescribing information. NICE Clinical Knowledge Summaries.

National Health Service. (n.d.). Diazepam. NHS. The NHS lists drowsiness, tiredness and reduced alertness among recognised adverse effects of diazepam.

NHS England / Right Decisions. (n.d.). Benzodiazepines and Z-drugs: Quality prescribing guidance. The guidance highlights tolerance, dependence and medication-related harms associated with these drugs.

National Health Service. (n.d.). Zopiclone. NHS. Residual tiredness, sleepiness and reduced alertness the following day are recognised adverse effects of sedative hypnotics.