Drug Interactions You Need to Know About with Amphetamine/Dextroamphetamine IR

Amphetamine/dextroamphetamine IR (generic Adderall) can interact with other medications, supplements, and even certain foods in ways that can be dangerous — or that reduce how well the medication works.

Knowing what to avoid and what to tell your doctor can help you stay safe and get the most out of your treatment. This guide covers the most important interactions to be aware of.

How Drug Interactions Work

A drug interaction happens when one substance changes how another substance works in your body. This can happen in several ways:

• Increased effects: One substance makes another more potent, raising the risk of side effects or toxicity.
• Decreased effects: One substance reduces the effectiveness of another, meaning your medication may not work as well.
• New side effects: The combination creates a reaction that neither substance would cause on its own.

Because amphetamine/dextroamphetamine IR affects brain chemicals (dopamine and norepinephrine) and the cardiovascular system, interactions can be especially serious. Always tell your doctor about everything you take — including prescriptions, over-the-counter medications, vitamins, and supplements.

Medications That Interact with Amphetamine/Dextroamphetamine IR

Major Interactions (Avoid or Use Extreme Caution)

• MAO inhibitors (MAOIs) — Including phenelzine (Nardil), tranylcypromine (Parnate), isocarboxazid (Marplan), and selegiline (Emsam). This combination is contraindicated. Taking amphetamine/dextroamphetamine IR with an MAOI — or within 14 days of stopping one — can cause a life-threatening hypertensive crisis (dangerously high blood pressure). This is the most dangerous interaction.
• Serotonergic medications — Including SSRIs like fluoxetine (Prozac), sertraline (Zoloft), and escitalopram (Lexapro); SNRIs like venlafaxine (Effexor) and duloxetine (Cymbalta); and triptans like sumatriptan (Imitrex). When combined with amphetamines, these medications increase the risk of serotonin syndrome — a potentially life-threatening condition with symptoms like agitation, high fever, rapid heart rate, muscle rigidity, and confusion. Many people do take an SSRI and a stimulant together under careful medical supervision, but it requires monitoring.
• CYP2D6 inhibitors — Medications like quinidine, fluoxetine (Prozac), and paroxetine (Paxil) can slow down how your body processes amphetamine, leading to higher levels in your blood and increased side effects.

Moderate Interactions (Use with Caution)

• Blood pressure medications — Amphetamines can raise blood pressure, which may counteract the effects of antihypertensives like lisinopril, amlodipine, or metoprolol. Your doctor may need to adjust your blood pressure medication dose.
• Tricyclic antidepressants (TCAs) — Medications like amitriptyline (Elavil) and nortriptyline (Pamelor) can have their effects enhanced by amphetamines, potentially leading to cardiovascular side effects.
• Antipsychotics — Haloperidol (Haldol), risperidone (Risperdal), and other antipsychotics may reduce the stimulant effects of amphetamine. Conversely, amphetamines may reduce the effectiveness of antipsychotics.
• Lithium — May reduce the stimulant effects of amphetamine/dextroamphetamine IR.
• Proton pump inhibitors (PPIs) — Omeprazole (Prilosec), esomeprazole (Nexium), and similar drugs can increase stomach pH, which may increase amphetamine absorption and raise drug levels.
• Alkalinizing agents — Sodium bicarbonate (baking soda) and antacids like Tums can increase amphetamine absorption and prolong its effects by making urine more alkaline.
• Acidifying agents — Vitamin C supplements and acidic medications can decrease amphetamine absorption and shorten its duration of action.

Supplements and OTC Medications to Watch

Not all interactions involve prescription drugs. Common over-the-counter products and supplements can also cause problems:

• Vitamin C (ascorbic acid) — Can reduce how well amphetamine/dextroamphetamine IR is absorbed and how long it lasts. Avoid taking large doses of vitamin C around the same time as your medication.
• Antacids (Tums, Rolaids) — Can increase amphetamine absorption, potentially raising the risk of side effects.
• Decongestants (pseudoephedrine, phenylephrine) — Found in many cold and allergy medications (Sudafed, Dayquil). These are also stimulants and can amplify cardiovascular effects like increased heart rate and blood pressure.
• Caffeine supplements — High-dose caffeine pills or pre-workout supplements combined with amphetamines can increase anxiety, jitteriness, heart rate, and blood pressure.
• St. John's Wort — This herbal supplement affects serotonin levels and may increase the risk of serotonin syndrome when combined with amphetamines.
• Antihistamines — Diphenhydramine (Benadryl) and similar medications may have reduced sedative effects when taken with stimulants.

Food and Drink Interactions

What you eat and drink can affect how amphetamine/dextroamphetamine IR works:

• Citrus juice (orange juice, grapefruit juice) — The acidity can reduce medication absorption. Avoid drinking citrus juice within an hour of taking your dose.
• Acidic foods — Foods high in vitamin C or citric acid (tomatoes, berries, citrus fruits) may decrease absorption if eaten at the same time as the medication.
• Caffeine — Coffee, energy drinks, and tea contain caffeine, which can add to the stimulant effects and increase heart rate, anxiety, and insomnia. Many people can tolerate moderate caffeine with their medication, but be mindful of how you feel.
• Alkaline foods — While less commonly discussed, highly alkaline foods or drinks could theoretically increase absorption. This isn't typically a practical concern for most diets.

For more information about side effects that can result from interactions, see our guide on amphetamine/dextroamphetamine IR side effects.

What to Tell Your Doctor

Before starting amphetamine/dextroamphetamine IR — and at every follow-up visit — make sure your doctor knows about:

• All prescription medications you currently take, including any you've stopped in the last 14 days (especially MAOIs)
• Over-the-counter medications — especially cold medicines, antacids, and pain relievers
• Vitamins and supplements — including vitamin C, St. John's Wort, and any herbal products
• Caffeine intake — how much coffee, tea, or energy drinks you consume daily
• Any new medications prescribed by other doctors. If you see multiple providers, make sure each one knows you're taking a stimulant.

If you're ever unsure whether something interacts with your medication, your pharmacist is an excellent resource. They have access to interaction-checking databases and can flag potential problems.

Final Thoughts

Amphetamine/dextroamphetamine IR is a safe and effective medication when used correctly — but it does interact with a number of other substances. The most critical one to know: never take it with or within 14 days of an MAOI. Beyond that, being upfront with your healthcare providers about everything you take is the best way to avoid problems.

If you have a prescription and need help finding it in stock, Medfinder can help you locate a pharmacy near you with amphetamine/dextroamphetamine IR available.