Patients who take drugs to treat attention deficit hyperactivity disorder (ADHD) should consult their physicians before taking any additional prescriptions, over-the-counter medications, nutritional supplements or herbal medications.

Stimulant drugs and alpha-2 adrenergic agonists are often combined to treat ADHD. There have been a handful of reported deaths in children who have taken this combination. However, an investigation by the U.S. Food and Drug Administration (FDA) found no significant danger in taking these drugs together.

Caffeine use can decrease the effectiveness of stimulants in treating ADHD. In addition, use of the antidepressant MAO inhibitors (MAOIs) with stimulants can cause severe high blood pressure (hypertension). Vitamin C supplements (ascorbic acid) may shorten the duration of the dosage.

Other drugs that may interact poorly with stimulants include:

• Antacids
• Anticonvulsants
• Anticoagulants (drugs that help prevent blood clots)
• Antidepressants (in addition to MAO inhibitors)
• Antipsychotics
• Bretylium tosylate (heart drug)
• Sedatives such as barbiturates

Drugs that may interact poorly with antidepressants used to treat ADHD include:

• Other antidepressants
• Certain blood pressure medications
• Sedatives such as benzodiazepines

Drugs that may interact poorly with alpha-2 adrenergic agonists used to treat ADHD include:

• Antidepressants
• Antihypertensives
• Central nervous system (CNS) depressants such as alcohol and sedatives
• Nonsteroidal anti-inflammatory drugs (NSAIDs)