What are the potential drug interactions between Fexofenadine (Allegra) hydrochloride and Adderall (Dextroamphetamine and Amphetamine)?

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Last updated: April 22, 2025 • View editorial policy

From the Guidelines

Fexofenadine (Allegra) and Adderall (amphetamine/dextroamphetamine) can generally be taken together, but it's crucial to monitor blood pressure due to the potential for Adderall to cause elevated BP, as noted in the 2018 guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1, 2.

Key Considerations

  • Fexofenadine is a non-drowsy antihistamine that treats allergy symptoms, while Adderall is a stimulant used for ADHD and narcolepsy.
  • Unlike older antihistamines, fexofenadine doesn't cross the blood-brain barrier significantly, so it doesn't cause drowsiness or interfere with Adderall's stimulant effects.
  • However, you should be aware that both medications may cause dry mouth as a side effect, which could be more noticeable when taking them together.
  • It's also important to note that acidic foods, juices, or beverages might reduce the absorption of both medications, so take them with water and avoid fruit juices within 4 hours of taking either medication.

Management Strategy

  • According to the guideline, amphetamines (eg, amphetamine, methylphenidate, dexmethylphenidate, dextroamphetamine) may cause elevated BP, and the possible management strategy is to discontinue or decrease the dose, and consider behavioral therapies for ADHD 1, 2.
  • Always inform your healthcare provider about all medications you're taking to ensure safe use.

Potential Interactions

  • There is no significant drug interaction between fexofenadine and Adderall, but monitoring blood pressure is essential due to the potential for Adderall to cause elevated BP.
  • Other medications, such as decongestants, NSAIDs, and systemic corticosteroids, may also interact with Adderall or fexofenadine, so it's essential to inform your healthcare provider about all medications you're taking.

From the Research

Fexofenadine HCl and Adderall Interaction

  • There is no direct evidence of a drug interaction between fexofenadine HCl and Adderall in the provided studies.
  • Fexofenadine HCl is an antihistamine that has been shown to have no significant effect on the corrected QT interval (QTc) even at high doses 3, 4.
  • Adderall is a stimulant medication used to treat attention deficit hyperactivity disorder (ADHD) and has been shown to be effective in reducing ADHD symptoms 5, 6.
  • A study comparing the stimulant effects of fexofenadine with modafinil and methylphenidate found that fexofenadine did not have significant stimulant effects, whereas methylphenidate improved performance in divided attention and vigilance tasks 7.
  • Since Adderall is a stimulant medication, it is possible that it may interact with other medications, including fexofenadine HCl, but the provided studies do not provide evidence of a specific interaction between these two medications.
  • It is always recommended to consult with a healthcare professional before taking any new medications, especially if you are already taking other medications, to discuss potential interactions and side effects.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.