Does Adderall interact with vitamin C?

Adderall (amphetamine-dextroamphetamine) and its extended-release version, Adderall XR, are two of the most well-known medications used to treat attention-deficit/hyperactivity disorder (ADHD). Adderall is also FDA approved to treat narcolepsy. These stimulant medications are very effective at improving inattention, impulsivity, and hyperactivity. However, acidic foods can interfere with the absorption of Adderall—and impact its efficacy. That includes citrus fruit and the ascorbic acid (aka vitamin C) they contain. Here’s how.

The interaction between vitamin C and Adderall

“Vitamin C increases the acidity of the stomach, which can affect how prescription medications like Adderall are absorbed and metabolized,” explains Nick Bach, Psy.D., a psychologist in Louisville, Kentucky. Adderall absorption is increased in an alkaline environment. The acidity of vitamin C and the foods containing it has the potential to alter the way the body absorbs Adderall.

Vitamin C seems innocuous—this antioxidant is found in your morning orange juice, grapefruit, lemons, limes, and immune system boosts, like Emergen-C. It may feel a bit surprising that it can impact powerful drugs like Adderall. In fact, some physicians have been surprised by the interaction, too. Peter Zafirides, a psychiatrist in Columbus, Ohio, says he frequently prescribes Adderall in his daily practice. When a few of his patients noticed changes in their ADHD symptoms after beginning certain vitamins, he began to investigate. It turns out that those individuals were taking a high dose of vitamin C with their Adderall. “This really opened my eyes,” Dr. Zafirides says.

The impact of vitamin C on the efficacy of Adderall

How effective the medication is can depend on how well your gastrointestinal tract takes in the Rx and how quickly it’s metabolized out of your body through your urine. Vitamin C changes the way your stomach and kidneys process amphetamine—triggering more to be excreted and less to be absorbed.

One of the reasons that the possible interactions of citric acid, ascorbic acid, and Adderall aren’t well known is that there isn’t enough research to indicate a strong or dangerous interaction. In fact, most of the studies demonstrating the link between the two have been done on mice and rats. More research on human subjects is needed to confirm how much vitamin C reduces the efficacy of Adderall—and to determine if it occurs for other stimulant ADHD medications, such as Ritalin (methylphenidate) and Vyvanse (lisdexamfetamine).

Considering the timing of vitamin C and Adderall intake

“If you’re taking Adderall and not [seeing] results, talk to your doctor about your diet and over-the-counter supplements to find out if there’s something that could be interfering with your prescription medication,” Dr. Zafirides recommends. They can help you determine the best timing of your medication and any food or pills containing vitamin C. That being said, you can follow a few rules of thumb.

1. Create a vitamin schedule. One approach is to take Adderall in the morning and vitamin C supplements in the evening. “Given that vitamin C is a fairly tolerable vitamin, I ask patients to take vitamin C in the evening with their dinner,” Dr. Zafirides says. “Most of my patients are many hours past their doses of Adderall during the day, and we can completely factor out the impact of vitamin C on their treatment.” In other words, taking Adderall only during the day and vitamin C only in the evening ensures that there are no potential interactions.
2. Take Adderall at least one hour before vitamin C. Other physicians recommend taking doses of Adderall and vitamin C, or any fruit juices containing it, at least an hour apart. “For optimal effectiveness, it’s advisable to take Vitamin C either several hours before or after Adderall,” Dr. Bach says. “This helps in ensuring that Adderall is absorbed properly.” This is a slightly more flexible approach that might work best for those who don’t have established mealtimes, but it may not be best for people who tend to get off their prescription medication or dietary supplement schedule.
3. Adjust your dosage: “I find that Adderall very quickly and effectively treats symptoms of inattention, distractibility, procrastination, and disordered executive function,” Dr. Zafirides says. If you’re working closely with your healthcare provider to adjust your diet and routine, but you’re still not having relief from your symptoms of ADHD or are experiencing common side effects of Adderall—like decreased appetite, weight loss, nervousness, stomachache, or difficulty sleeping—your dose may need to be tweaked.

If you experience any adverse effects from your prescription, reach out to your healthcare team for medical advice.

The bottom line: Don’t stress about vitamin C

If you accidentally wash down your prescription medication with a glass of orange juice, don’t panic. On the scale of drug interactions, the one between vitamin C and Adderall is very minor. The worst thing that could happen is that the medication will be metabolized inefficiently, and its effectiveness will be reduced. It’s a minimal interaction that you can work with your pharmacist or another healthcare professional to find strategies to avoid while still getting all of the nutrients your body needs.