Lisdexamfetamine Drug Interactions: What to Avoid and What to Tell Your Doctor

Lisdexamfetamine Drug Interactions You Need to Know About

Lisdexamfetamine (brand name Vyvanse) is an effective medication for ADHD and Binge Eating Disorder, but like all medications, it can interact with other drugs, supplements, and even certain foods. Some of these interactions are dangerous. Others can make Lisdexamfetamine less effective or increase side effects.

This guide covers the most important interactions to be aware of and what you should tell your doctor before starting treatment.

How Drug Interactions Work

Drug interactions happen when one substance changes how another substance works in your body. With Lisdexamfetamine, interactions can:

• Increase the effects of Lisdexamfetamine (raising the risk of side effects or overdose)
• Decrease the effects of Lisdexamfetamine (making it less effective)
• Create dangerous new effects that neither drug would cause on its own (like serotonin syndrome or hypertensive crisis)
• Change how other medications work (Lisdexamfetamine can reduce the effectiveness of some drugs)

Major Drug Interactions (Avoid or Use With Extreme Caution)

The following interactions are the most serious. Some are contraindicated, meaning the two medications should never be used together:

MAO Inhibitors — Contraindicated

Medications: Phenelzine (Nardil), Tranylcypromine (Parnate), Isocarboxazid (Marplan), Selegiline (Emsam), Rasagiline (Azilect), Linezolid (Zyvox — an antibiotic that has MAOI activity)

Taking Lisdexamfetamine with an MAO inhibitor — or within 14 days of stopping one — can cause a hypertensive crisis (dangerously high blood pressure). This combination is absolutely contraindicated. Tell your doctor if you've taken any MAOI in the past two weeks.

Serotonergic Medications — Serotonin Syndrome Risk

Medications: SSRIs like Sertraline (Zoloft), Fluoxetine (Prozac), Escitalopram (Lexapro); SNRIs like Venlafaxine (Effexor), Duloxetine (Cymbalta); Triptans like Sumatriptan (Imitrex); and others that increase serotonin

Combining Lisdexamfetamine with serotonergic drugs increases the risk of serotonin syndrome — a potentially life-threatening condition with symptoms including agitation, rapid heartbeat, high body temperature, muscle twitching, and confusion. Many people do take an SSRI and Lisdexamfetamine together, but it requires careful monitoring by your doctor.

Alkalinizing Agents — Increased Amphetamine Levels

Substances: Sodium Bicarbonate (baking soda), antacids (Tums, Maalox), Acetazolamide

Alkalinizing agents raise the pH of your urine, which slows the elimination of Amphetamine from your body. This can increase Lisdexamfetamine's effects and raise the risk of side effects or toxicity.

CYP2D6 Inhibitors — Increased Amphetamine Exposure

Medications: Fluoxetine (Prozac), Paroxetine (Paxil), Bupropion (Wellbutrin), Quinidine

These drugs slow down the CYP2D6 enzyme that helps metabolize Amphetamine. Taking them with Lisdexamfetamine may increase Amphetamine levels in your blood, leading to stronger effects and more side effects.

Moderate Drug Interactions

These interactions are not contraindicated but require monitoring and possible dose adjustments:

Antihypertensives (Blood Pressure Medications)

Medications: Lisinopril, Amlodipine, Metoprolol, Losartan, and others

Lisdexamfetamine can raise blood pressure, which may reduce the effectiveness of blood pressure medications. If you take antihypertensives, your doctor should monitor your blood pressure closely after starting Lisdexamfetamine.

Tricyclic Antidepressants

Medications: Amitriptyline (Elavil), Nortriptyline (Pamelor), Desipramine (Norpramin)

Tricyclics can enhance the effects of Amphetamine, potentially leading to increased cardiovascular side effects. Dose adjustments may be needed.

Acidifying Agents — Decreased Amphetamine Levels

Substances: Ascorbic Acid (Vitamin C), acidic fruit juices

Acidifying agents lower urine pH, which speeds up the elimination of Amphetamine from your body. This can make Lisdexamfetamine less effective. Avoid taking large doses of Vitamin C around the same time as your medication.

Phenobarbital and Phenytoin (Anti-Seizure Medications)

These may have altered blood levels when taken with Amphetamines. Your doctor should monitor drug levels if you're on both.

Lithium

Lithium may reduce the stimulant effect of Lisdexamfetamine. Monitoring is recommended.

Proton Pump Inhibitors (PPIs)

Medications: Omeprazole (Prilosec), Pantoprazole (Protonix), Esomeprazole (Nexium)

PPIs may affect the absorption of Lisdexamfetamine by altering stomach pH. The clinical significance varies, but it's worth mentioning to your doctor.

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Supplements and Over-the-Counter Medications to Watch

• Vitamin C (Ascorbic Acid) — Large doses can reduce Lisdexamfetamine's effectiveness. Avoid taking Vitamin C supplements at the same time as your medication.
• Caffeine — While not a dangerous interaction, combining caffeine with Lisdexamfetamine can increase anxiety, jitteriness, and heart rate. Many doctors recommend limiting caffeine intake.
• Decongestants (Pseudoephedrine, Phenylephrine) — Found in many cold medications. Combining with Lisdexamfetamine can increase blood pressure and heart rate.
• St. John's Wort — Has serotonergic activity and could increase the risk of serotonin syndrome when combined with Lisdexamfetamine.
• Melatonin — Generally considered safe to take with Lisdexamfetamine and may actually help with stimulant-related insomnia. Still, tell your doctor.

Food and Drink Interactions

• Acidic foods and beverages — Orange juice, grapefruit juice, and other acidic drinks taken around the time of your dose may reduce how well Lisdexamfetamine works. It's best to avoid large amounts of acidic foods or drinks within an hour of taking your medication.
• Alkaline foods — Conversely, alkaline foods may increase absorption. This is generally not a clinical concern for most people eating a normal diet.
• Alcohol — Alcohol is a depressant that can mask the effects of Lisdexamfetamine and impair judgment. Combining the two is generally not recommended.
• Food in general — Lisdexamfetamine can be taken with or without food. Food does not significantly affect its absorption since the prodrug conversion happens in the bloodstream, not the stomach.

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What to Tell Your Doctor

Before starting Lisdexamfetamine, give your doctor a complete list of:

• All prescription medications you're taking, including psychiatric medications, blood pressure drugs, and anti-seizure medications
• Over-the-counter medications, including antacids, decongestants, and pain relievers
• Supplements and vitamins, especially Vitamin C, St. John's Wort, and herbal products
• Recreational substances, including alcohol and caffeine consumption
• Any recent medication changes, including stopping an MAOI in the past 14 days

Don't assume your doctor knows about every medication you take, especially if you see multiple providers. Keeping an updated medication list on your phone is a simple way to avoid dangerous gaps in communication.

Final Thoughts

Most people take Lisdexamfetamine safely, even alongside other medications. The key is making sure your doctor knows everything you're taking so they can monitor for interactions and adjust doses as needed. When in doubt, ask your pharmacist — they're drug interaction experts.

For more about Lisdexamfetamine, check out our complete guide or learn about side effects to watch for. Need to find it in stock? Try Medfinder.