What Are The Phentermine Side Effects?

Along with the weight loss effects you desire, phentermine may cause some unwanted side effects.



Please consult your doctor immediately if you notice any of the following signs that you may be suffering from an adverse reaction to Phentermine.

Major Phentermine Side Effects

If any of the following Phentermine side effects occur while taking the drug, please check with your doctor immediately:


  • Seeing, hearing, or feeling things that are not there
  • Severe mental changes
  • Chest pain
  • Decreased ability to exercise
  • Dizziness
  • Fainting
  • Fast, irregular, pounding, or racing heartbeat or pulse
  • Headache numbness or tingling in the arms or legs
  • Swelling of the feet or lower legs
  • Trembling or shaking of the legs, arms, hands, or feet
  • Trouble breathing
  • Trouble with thinking, speaking, or walking weakness

​If there is the worry that you might suffer from one of these side effects of phentermine, you might want to consider using an alternative to phentermine instead. Our official recommendation at Phenobestin.com is Phenobestin 37.5, an extremely efficient weight loss supplement that will help you jump start your weight loss journey, while avoiding side effects of Phentermine such as what is listed above.

Minor Phentermine Side Effects

Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

  • Decreased libido
  • Difficulty having a bowel movement (stool)
  • Dryness of mouth false or unusual sense of well-being breaking out into hives or welts
  • Difficulty having or keeping an erection increased libido or sexual performance increased interest in sexual intercourse. Some people chose to take Viagra or Horny Goat Weed supplements, but it might not help all the time.
  • Itching
  • Loss of sexual ability or desire
  • Skin redness
  • Skin rash
  • Unpleasant taste
  • Web MD - Phentermine Oral : Uses, Side Effects, Interactions, Pictures, Warnings and Dosing - WebMD.
  • Drugs.com - Phentermine: Drug Uses, Dosage and Side Effects - Drugs.com.
  • Mayoclinic.org - Phentermine for weight loss - Mayo Clinic.
  • MedinePlus.gov- Phentermine: MedlinePlus Drug Information
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  • MedicineNet.com - Phentermine Weight Loss Drug Side Effects, Dosage, Safety & Alcohol Effects.
  • RXList.com - Phentermine (phentermine hydrochloride): Side Effects, Dosages, Treatment, Interactions, Warnings
  • EverydayHealth.com - Phentermine Reviews - Everyday Health
  • HealthLine.com - Phentermine - Side Effects, Dosage, Uses, and More.

(Last Updated On: 22nd September 2021)