Is it safe to take phentermine (Adipex) and Adderall (amphetamine and dextroamphetamine) together?

Concurrent Use of Phentermine and Adderall is Not Safe and Should Be Avoided

Concurrent use of phentermine and Adderall (amphetamine-dextroamphetamine) is contraindicated due to significant risks of adverse cardiovascular effects, central nervous system overstimulation, and potential for abuse.

Pharmacological Concerns

• Both medications are sympathomimetic amines with similar mechanisms of action, stimulating the release of norepinephrine and affecting both α- and β-adrenergic receptor sites 1
• Phentermine is chemically and pharmacologically related to amphetamine, which is a component of Adderall 2
• The combination can lead to additive stimulant effects, potentially causing dangerous increases in blood pressure, heart rate, and risk of cardiovascular events 3, 2
• Phentermine is contraindicated for use in combination with monoamine oxidase inhibitors and other sympathomimetic amines, which would include Adderall 3, 2

Cardiovascular Risks

• Combined use may significantly increase the risk of:
  • Hypertension 2
  • Tachycardia 1
  • Cardiac arrhythmias 3
  • Potential for primary pulmonary hypertension 2
  • Valvular heart disease 2

Neurological and Psychiatric Risks

• Concurrent use can lead to:
  • Increased risk of seizures 1
  • Severe anxiety and agitation 4
  • Insomnia 3
  • Potential for psychosis with high doses 4

Abuse and Dependence Concerns

• Both medications are DEA Schedule II (Adderall) and IV (phentermine) controlled substances with high potential for abuse 2, 1
• Combined use may increase the risk of psychological and physical dependence 2
• The FDA specifically warns against coadministration of phentermine with other drug products for weight loss 2

Special Considerations

• Patients with even mild hypertension should use caution with phentermine alone, making the combination with Adderall particularly risky 2
• Patients with cardiovascular disease, hyperthyroidism, or glaucoma should absolutely avoid this combination 2
• Women of reproductive potential should be counseled about the risks, as both medications are contraindicated in pregnancy 3

Monitoring If Absolutely Necessary

If for some reason a patient must take both medications (which is strongly discouraged):

• More frequent monitoring of vital signs, particularly blood pressure and heart rate 5
• Regular electrocardiogram monitoring 2
• Use the lowest effective doses of both medications 5
• Monitor for signs of abuse or dependence 2
• Consider alternative medications for either condition 5

Alternative Approaches

• For ADHD in adults who need weight management:
  • Consider non-stimulant ADHD medications like bupropion 3
  • Consider behavioral interventions for either condition 3
• For weight management in adults with ADHD:
  • Consider non-stimulant weight loss medications like orlistat, naltrexone/bupropion, liraglutide, or semaglutide 3

The concurrent use of these medications represents a significant risk with limited additional benefit compared to using either medication alone. The potential for serious adverse events, including cardiovascular complications, far outweighs any potential benefits of combination therapy.