Is it safe to use phentermine (anorexiant) and Adderall (amphetamine and dextroamphetamine) together?

Concurrent Use of Phentermine and Adderall is Contraindicated Due to Serious Health Risks

The concurrent use of phentermine and Adderall is strongly contraindicated due to potentially dangerous additive sympathomimetic effects that can significantly increase the risk of serious cardiovascular events, including hypertensive crisis, arrhythmias, and stroke. 1, 2

Pharmacological Concerns

Overlapping Mechanisms and Risks

• Both medications are sympathomimetic amines with similar mechanisms of action:
  • Phentermine is an anorectic that increases norepinephrine release 2
  • Adderall (amphetamine/dextroamphetamine) acts on dopamine and norepinephrine systems
  • Combined use creates dangerous additive effects on the cardiovascular and central nervous system

Specific Cardiovascular Risks

• Concurrent use can lead to:
  • Severe hypertension
  • Tachycardia and palpitations
  • Increased risk of stroke
  • Potential for myocardial infarction
  • Dangerous arrhythmias

CNS Effects

• Combined stimulant effects may cause:
  • Severe insomnia
  • Extreme anxiety and agitation
  • Psychosis
  • Increased seizure risk

Contraindications and Guidelines

The American Diabetes Association specifically notes that phentermine is contraindicated for use in combination with monoamine oxidase inhibitors 1. While Adderall is not a MAOI, the principle of avoiding combinations of sympathomimetic agents applies due to similar safety concerns.

Phentermine itself has significant cardiovascular considerations:

• Increases heart rate and blood pressure 2
• Associated with palpitations 2
• Not recommended for patients with cardiovascular disease 2

Alternative Approaches

For patients requiring treatment for both ADHD and obesity, safer alternatives include:

For Weight Management:

• Non-stimulant options such as:
  • Orlistat 1, 2
  • Naltrexone/bupropion ER (with caution in patients with seizure disorders) 1
  • GLP-1 receptor agonists like liraglutide or semaglutide 1

For ADHD Management:

• If a patient requires obesity management while on Adderall:
  • Consider non-stimulant weight loss medications
  • Focus on comprehensive lifestyle modifications
  • If pharmacotherapy is necessary, consult with both psychiatrist and weight management specialist

Monitoring and Risk Mitigation

If a patient is transitioning from one medication to another (never using both concurrently):

• Ensure complete washout of one medication before starting the other
• Monitor blood pressure and heart rate closely during transition
• Watch for withdrawal effects when discontinuing either medication
• Implement a structured tapering schedule when discontinuing either medication 2

Common Pitfalls to Avoid

1. Assuming "more is better": Some patients or providers might incorrectly assume that combining two medications with similar mechanisms will enhance weight loss without understanding the dangerous additive effects.

2. Inadequate screening: Failure to screen for cardiovascular risk factors before prescribing either medication individually.

3. Pharmacy oversight: Patients may receive these medications from different providers who are unaware of the other prescription, highlighting the importance of medication reconciliation.

4. Off-label use: Phentermine is only approved for short-term use (≤12 weeks) 2, but is often prescribed long-term, increasing the risk of drug interactions 3.