As well as physical side effects such as constipation and headaches, phentermine can cause a range of psychological side effects. Although depression is listed as a less common phentermine side effect, our forum shows that many users experience this reaction. So, if you’re taking phentermine and are experiencing low mood, sadness, hopelessness or disinterest, then you’re not alone.  Here we explain why phentermine can cause depression and how to combat this side effect for a better phentermine experience.

Why Does Phentermine Cause Depression?

There are three main theories to explain why phentermine causes depression:

Phentermine Overstimulates Neurotransmitters

It is thought that phentermine can cause depression due to the way it activates neurotransmitters in the brain, causing them to become overstimulated. For some people this can result in feelings of euphoria and positivity. But unfortunately other phentermine patients can experience the downside of this over-stimulation, leading to low mood and depression.

Phentermine Amplifies Emotional Reactions

Another theory is that, as a stimulant, as well as increasing your energy levels, phentermine magnifies your feelings and emotions. This then amplifies your normal reactions to situations into extreme feelings ranging from anger to depression. This can explain why people who have experienced depression in the past may be more susceptible to this side effect. However, low mood and depression are also experienced by patients who have no previous experience of these symptoms.

Phentermine Causes Hormonal Fluctuations

Lastly, depression on phentermine may be due to the way that the dramatic weight loss often experienced on phentermine can affect hormones. Rapid weight loss causes fluctuations in hormone levels as the release of estrogen is partly based on the amount of fat cells in the body. Hormonal fluctuations can then result in low mood and depression in the same way that some women experience while suffering from pre-menstrual syndrome (PMS) pregnancy, perimenopause and/or menopause.

How To Combat Depression On Phentermine

If you are experiencing depression on phentermine, taking these steps should help you to manage and reduce this side effect:

1. Talk It Over

Talk to someone close to you about how you’re feeling. Depression doesn’t have to have an explanation or a solution, but there may be something else triggering this reaction. Vocalizing and sharing your inner feelings with an understanding friend can help to put things in perspective and should make you feel less alone. It can help to recognize that phentermine may be amplifying your emotions but that doesn’t make your depression any less valid. If you’ve decided not to tell anyone about taking phentermine then our forum is a great way to connect with others on phentermine, some of whom may be experiencing similar side effects. Lastly, if you don’t feel prepared to share your feelings yet, even anonymously online, then writing things down can help to make your emotions more tangible. Once you’ve done that then you may be more prepared to speak to someone about what you’re feeling.

2. Sleep On It

It’s a cliché but overcoming challenges often seems more possible after some rest. A lack of sleep leaves us feeling low and mentally exhausted, making small problems seem more difficult to resolve. Studies into the link between sleep and depression show that people with insomnia are ten times more likely to experience depression. Therefore, the common phentermine side effect of insomnia can heighten feelings of depression.  Follow this advice to combat insomnia, and be sure to talk to your doctor if insomnia persists, as he or she may advise a reduction in your dosage to minimize side effects.

Similarly, depression can be the cause of sleep problems; some depressed patients may find that they are unable to sleep while others are fatigued and tend to sleep more. Phentermine should increase motivation and energy so if you find that your sleeping patterns have changed or that you’re more tired than usual then speak to your doctor.


3. Get An Exercise Boost

Exercise is a great mood booster thanks to the endorphins a good workout releases. So, as well as boosting weight loss, and many other benefits, getting active while taking phentermine could really help to reduce depression. One study found that depression sufferers who did aerobic exercise showed just as much improvement in their symptoms as people on medication. And, these mood-lifting added benefits of exercise can be seen straight away; 20 minutes of activity is enough to elevate your mood and increase feelings of positivity. The workout doesn’t even have to be intense, so choose an exercise you like and ride the exercise high for hours!

4. Eat Feel-Good Foods

Your diet contributes to your mood more than you realize. Many of us reach for comfort foods like ice cream or fried foods when we’re feeling low but this kind of emotional eating is bad for both our physical and mental health. Instead, stock up on feel-good foods such as bananas, Brazil nuts, oily fish, whole grain pasta, lentils, yogurt, eggs, dark chocolate, and spinach. These foods are rich in various minerals and vitamins, such as selenium, magnesium, and B vitamins which contribute to an increase in serotonin production and improvements in mood. You may also need to take supplements to ensure that you get your vitamins while eating a calorie-controlled diet on phentermine. In addition, the supplement 5-HTP has been found to improve mood and also helps to boost the effectiveness of phentermine.

5. Prioritize Your Own Wellbeing

It’s important that you put your own health and wellbeing first, especially if you are struggling with low mood and negative feelings. Indulge in non-food related treats such as a soothing massage, and avoid taking on too much; say no to things and prioritize important tasks by keeping a to-do list. Stress and anxiety can also contribute to and worsen depression; take steps to reduce stress by following these stress-management techniques. Simple changes such as taking up a relaxing hobby or listening to your favorite music can really help. Furthermore, reducing stress also helps boost weight loss since stress has an adverse effect on cortisol production and hunger signals.

6. Seek Professional Help

Whether it’s a side effect caused by phentermine or a manifestation of something deeper, depression often can’t be managed alone. Most phentermine side effects start to subside after a week or two. So, if feelings of depression persist then you should speak to your doctor. He or she may decide to reduce your dosage or switch you to a different medication. But if the depression remains a problem for you then you might find it helpful to seek professional help. Ask your doctor for advice or for a referral to a psychologist.


If you find the side effect of depression difficult then you may want to try a weight loss supplement instead. We recommend Phen Caps, which suppress appetite and boost energy but have no side effects and no health risks. As the leading phentermine alternative, Phen Caps can help you achieve the results you want but without the negatives associated with phentermine.

Have you experienced depression on phentermine? Do you have any advice for other phentermine users experiencing this side effect? Let us know by commenting below.


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4 Responses

  1. I have multiple sclerosis. Can phentermine have any negative effects like causing relapses?

    • Hi Dana,
      We’re not sure about links between phentermine and conditions like MS so it’s best that you ask your doctor for advice.

  2. what happens when you come off the Phentermine after being on it over a month??

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