Taking Phentermine With Adderall

There is a significant interaction between phentermine and Adderall (mixed amphetamine salts). In the vast majority of cases, they should not be taken together.

Both phentermine and Adderall are stimulant medications, classified as sympathomimetics. They have very similar effects on the body, such as increasing the amount of various neurotransmitters in the brain, such as dopamine and norepinephrine.

Taking more than one sympathomimetic drug, such as phentermine with Adderall can greatly increase the risk of serious cardiovascular and other side effects, including:

• Increased blood pressure
• Increased heart rate
• irritability
• Serotonin syndrome
• Tremors
• Nausea
• Vomiting
• Headache
• Restlessness
• Overstimulation
• Palpitations
• Loss of coordination
• Dizziness

Below, I discuss additional information about both drugs and dive a little deeper into the concerns with taking them together.

Adderall

Adderall is a mixture of both amphetamine and dextroamphetamine salts and is used mainly to treat attention-deficit hyperactivity disorder (ADHD).

Adderall works by stimulating the release of neurotransmitters such as dopamine, norepinephrine, and serotonin.

This neurotransmitter release has a variety of noticeable effects, including:

• Decreased fatigue
• Increased mental alertness
• Increased motor activity
• Improved mood
• Suppression of appetite

It is available as both an immediate-release tablet and as an extended-release capsule (Adderall XR).

Phentermine

Phentermine is chemically similar to amphetamine and also has a similar mechanism of action.

In fact, it is commonly described as having "amphetamine-like" effects on mood.  It is commonly used for weight loss, in conjunction with diet and exercise.

Phentermine is relatively long-lasting and should be dosed in the morning to prevent sleeping problems at bedtime.

Taking Phentermine With Adderall: Concerns

As discussed above, phentermine should not be used with Adderall due to the potential for additive side effects. Using both together can significantly increase the risk of increased heart rate, blood pressure, and rarely, serotonin syndrome. Let's take a look at some of these potential side effects in more detail.

Blood Pressure

Phentermine and Adderall both increase blood pressure and can increase the risk of cardiovascular events, like heart attack and stroke.

The prescribing information for Adderall XR states that, in general, stimulant medications can increase heart rate and cause an average increase in blood pressure of about 2 to 4 mmHg:

Stimulant medications cause a modest increase in average blood pressure (about 2-4 mmHg) and average heart rate (about 3-6 bpm), and individuals may have larger increases.

Combining stimulates likely increases the risk of these effects even more.

If you already have high blood pressure or pre-existing heart conditions, combining stimulants could be especially dangerous.

Serotonin Syndrome

Serotonin syndrome is a rare but serious disorder that results from excess serotonin in the brain. If it occurs, immediate medical attention is required.

It isn't overly common, but the risk is greatly increased if you are taking more than one drug that has serotonergic effects

The symptoms of serotonin syndrome include:

• Hyperthermia (increased body temperature)
• Hypertension (increased blood pressure)
• Muscle spasms
• Muscle rigidity
• Mental status changes (e.g., agitation, delirium, hallucinations, coma)

The prescribing information for both phentermine and Adderall warn about serotonin syndrome and recommend not to combine them with other serotonergic agents.

Overstimulation

Since Adderall and phentermine are both stimulants, there is a risk of overstimulation with combined use. This may manifest as:

• Restlessness
• Tremors
• Headache
• Nausea
• Insomnia
• Twitchiness
• Dizziness

If any of the above side effects occur, even with a single drug (i.e. either Adderall or phentermine), it is generally recommended to reduce your dose.

Final Words

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