Phentermine and Depression

This article is intended for informational purposes only.

We are not doctors, and the information below does not in any way constitute or substitute a professional medical opinion. Always contact a licensed medical professional for medical advice.

Apart from heart problems, phentermine psychological side effects are some of the most potentially-troublesome reactions. Phentermine and depression are an especially common and worrisome duo, so it is important to monitor yourself and loved ones for signs of hopelessness or suicidal tendencies.

In fact, even though low mood is considered a rare side effect of this medication, recent data indicates that approximately 1 in 6 users have experienced phentermine depression or anxiety during their weight loss journey ( 1 ).

Patients taking phentermine and topiramate together (e.g. Qsymia) are at an even higher risk for suicidal thoughts or actions ( 2 ).

Contact a doctor immediately if you or someone close to you experiences any of the following while taking phentermine weight loss pills:

  • Dramatic mood swings
  • Extreme happiness
  • Extreme sadness
  • Hopelessness
  • Nervousness
  • Other atypical emotional changes

Why Does Phentermine Cause Depression?

Woman suffering from phentermine psychological side effects
Phentermine’s psychological side effects include depression and mood changes

Low mood from phentermine varies in severity: ranging from mildly bothersome sadness to severe, debilitating depression. Unfortunately, the exact cause of phentermine depression remains unknown.

However, there are three potential explanations for phentermine depression:

1. Overstimulation

Research indicates that prolonged stimulant exposure can cause depression related to the repeated release of critical neurotransmitters.

Phentermine affects natural levels of norepinephrine, dopamine, and serotonin (the catecholamines). As a stimulant, it elevates these hormones, and patients experience a boost in mood and energy – at least at first.

However, in some cases, prolonged exposure to high levels of dopamine can cause depression ( 3 ). If you are experiencing phentermine depression several weeks or months into treatment, this may at least partially explain your low mood.

2. Amplified Emotions

Many phentermine users also report that this medication amplifies emotional reactions in all directions. As a result, people with a history of depression or other mental health problems may be more susceptible to phentermine psychological side effects ( 4 ).

That being said, patients with no history of mental health problems can also suffer from low mood and phentermine depression while taking this medication.

3. Hormonal Fluctuations

Depression while taking phentermine could also be related to hormonal changes associated with major weight loss.

For example, dramatic fluctuations in hormones like estrogen can precipitate periods of low mood and anxiety. If you suspect hormonal changes as a contributing factor in your phentermine depression, speak with a doctor about possible solutions.

Be honest with yourself, your loved ones, and your medical team about the presence and severity of emotional side effects during your weight loss journey, and ask for help when you need it.

Depression While Taking Phentermine and Topiramate

woman taking a pill
Talk to a doctor if you have depression while taking phentermine & topiramate (Qsymia)

Qsymia is a popular weight loss pill that contains two active ingredients: phentermine hydrochloride and topiramate extended-release.

The chemicals work together to promote weight loss. Phentermine acts as a powerful CNS stimulant to suppress appetite and boost energy, while topiramate (an antileptic drug) helps control cravings and make food less appealing.

The second ingredient, topiramate, has been linked with an increased risk of depression and suicidal ideation.

In an analysis of almost 200 clinical trials, patients taking antiepileptic drugs like topiramate were twice as likely to experience suicidal behavior or ideation, when compared to patients taking a placebo (sugar pill). This dangerous side effect begins about one week after starting topiramate or Qsymia and persists throughout the course of treatment ( 2 ).

Contact a doctor right away if you or a loved one experiences any dramatic change in mood or mental status while taking phentermine and topiramate or Qsymia.

How to Cope with Phentermine Depression

Depression is a documented side effect of this medication. Seek help if you are feeling unusually emotional or down.

Talk to a doctor right away if you notice signs or symptoms of phentermine depression in yourself or a loved one. 

That being said, if your low mood is a more mild, passing sadness that feels like it can be reasonably managed at home, consider these strategies to combat less severe phentermine mental side effects:

man and woman holding hands
Ask for help if you have phentermine psychological side effects, such as depression

Talk About It

Vocalizing your feelings can help put things in perspective and make you feel less alone. It also proves helpful to remember that phentermine may be amplifying your emotions and making things seem more overwhelming than usual.

If you do not have anyone to confide in in person, the support group on Facebook is a great way to connect with other phentermine users, who may be facing similar challenges.

If you prefer to keep things to yourself, journaling can be a great tool too!

Make Time to Sleep

It sounds cliché, but life’s challenges often seem less overwhelming after a good night’s sleep.

Even scientific research shows that depression and insomnia are tightly linked. Higher rates of insomnia are observed among depressed patients, while patients with insomnia often report worse depressive symptoms ( 5 ).

Speak to your doctor if your sleeping patterns have changed or you are much more tired than usual – especially if you are also feeling down.

Go for a Walk

Exercise is a natural mood booster.

During a good workout, the brain produces extra feel-good chemicals that improve mood and reduce stress & anxiety ( 6 ).

While all types of workouts help, team sports, cycling and aerobic classes or going to the gym are correlated with the greatest reduction in poor mental health days ( 7 ).

Eat Right

Many people reach for comfort foods like ice cream or fried foods when they feel low, but unhealthy emotional eating is detrimental to both your physical and your mental health.

Instead, stock up on feel-good foods like bananas, Brazil nuts, oily fish, whole grains, lentils, yogurt, eggs, dark chocolate, and spinach. These items are rich in vitamins and minerals that contribute to higher serotonin production and improvement in mood.

Prioritize Self-Care

Give yourself permission to put your own health and well-being first, especially if you’re struggling with low mood associated with phentermine and depression.

Reduce stress and anxiety by finding a relaxing hobby, listening to your favorite music, indulging in a soothing massage, or just taking a few hours of “me time” to rest and recharge each week.

Ask for Help

Whether it is a phentermine side effect or a manifestation of something deeper, depression is often too big to manage alone.

Speak to your doctor if feelings of phentermine depression persist, worsen or interfere with your daily life.

He or she may try reducing your dosage or switching you to a different medication, but if the low mood remains, it is prudent to seek professional mental health support. Your prescribing doctor may be able to offer advice, but you may also consider asking him or her for a referral to a psychologist.

Back to All Phentermine Side Effects

  1. Members of “Losing Weight with Phentermine” Support Group on Facebook & Forum. (2019, March 13). [User Report of Common Phentermine Side Effects]. Unpublished raw data.
  2. VIVUS, Inc. (2017). Highlights of Prescribing Information.
  3. Neel, A.B., Jr. (2012, February). Medications That Can Cause Depression.
  4. U.S. Food and Drug Administration. (2012). Adipex-P (phentermine hydrochloride) capsules label [Brochure].
  5. Nutt, D., Wilson, S., & Paterson, L. (2008). Sleep disorders as core symptoms of depression. Dialogues in Clinical Neuroscience, 10(3), 329-36.
  6. Mayo Clinic Staff. (2018, December 14). 7 great reasons why exercise matters.
  7. Chekroud, S. R., Gueorguieva, R., Zheutlin, A. B., Paulus, M., Krumholz, H. M., Krystal, J. H., & Chekroud, A. M. (2018). Association between physical exercise and mental health in 1·2 million individuals in the USA between 2011 and 2015: A cross-sectional study. The Lancet Psychiatry, 5(9), 739-746. doi:10.1016/s2215-0366(18)30227-x