Diet Pills are prescription or over-the-counter pills that help you lose weight by boosting your energy levels, stimulating your metabolism and suppressing appetite. 

Despite their benefits, there are certain diet pills side effects associated with some fat loss supplements that you should be aware of:

Common Side Effects of Diet Pills

  • Increased heart rate

Diet pills speed up your metabolism, leading to an increased heart rate. This can weaken your heart muscle which will lead to heart failure. The stimulants in the pills can increase heart rate and make the blood pressure drop low.

  • Liver Damage

Weight loss pills are not recommended for people with a liver problem to avoid creating any further damage. This is because some diet pills have been reported to cause an acute liver failure which might result in death. (1)

  • Insomnia

Some fat burning pills contain coffee. It has a lot of stimulants that might keep you awake at night. The stimulants’ ability to increase energy level can also affect your sleep, resulting in insomnia.

  • Dizziness

One of the side effects of using a diet pill is dizziness. Some over-the-counter weight loss pills contain PPA (Phenylpropanolamine) which enhances dizziness. It can also make you feel weak.

  • It may further damage the kidneys

Another common diet pills side effect is a potential further kidney damage. This is why fat loss pills are not always recommended for people with chronic kidney disease. Rather than taking diet pills, people with kidney problems can adopt another weight loss plan such as a low-calorie and a low-protein diet plan. (2)

  • Diarrhea

Diarrhea comes as a side effect of some diet pills. This can be unsafe for your health because you will lose some amount of water in the body which can lead to dehydration, weakness and loss of electrolytes. 

  • Rectal bleeding

Some diet pills can cause colon ischemia also known as rectal bleeding. It is not advisable to use this pill for a long time. If you take more than the recommended dose, it is more likely that you will experience rectal bleeding. 

  • Headache

Headaches are one of the side effects of taking fat burners. Pills that also affect neurotransmitters in the brain can be linked with a headache. This side effect is common with a pill like Contrave. 

  • Anxiety

Some ingredients in diet supplements and appetite suppressants over the counter enhance anxiety, paranoia and mood swings.

For instance, green tea extracts and guarana contain a high amount of caffeine which produces negative effects that cause anxiety. Other side effects such as agitation, paranoia, mood swings and nervousness can occur if the pill is misused.

  • Stomach side effects

Fat loss pills can come with stomach side effects such as nausea, vomiting and constipation. 

  • High blood Pressure

Some weight control supplements can cause high blood pressure because the pills may make your heart work harder which might cause adverse effects to the heart.


Although diet pills have been shown to help with weight loss, it is important to note that there are diet supplements that are dangerous because they contain harmful ingredients that may cause irreparable damage to one’s health.

This is why it is quite important to choose weight loss pills which contain natural ingredients that have been clinically tested and proven to be safe for consumption.

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