Adipex-P Side Effects
Generic Name: phentermine
Note: This document contains side effect information about phentermine. Some of the dosage forms listed on this page may not apply to the brand name Adipex-P.
Some side effects of Adipex-P may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.
For the Consumer
Applies to phentermine: oral capsule, oral capsule extended release, oral tablet, oral tablet disintegrating
Along with its needed effects, phentermine (the active ingredient contained in Adipex-P) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur while taking phentermine:Rare
- Seeing, hearing, or feeling things that are not there
- severe mental changes
- Chest pain
- decreased ability to exercise
- fast, irregular, pounding, or racing heartbeat or pulse
- 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
Some side effects of phentermine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:Incidence not known
- Decreased interest in sexual intercourse
- difficulty having a bowel movement (stool)
- dry mouth
- false or unusual sense of well-being
- hives or welts
- inability to have or keep an erection
- increased in sexual ability, desire, drive, or performance
- increased interest in sexual intercourse
- loss in sexual ability, desire, drive, or performance
- redness of the skin
- skin rash
- unpleasant taste
For Healthcare Professionals
Applies to phentermine: compounding powder, oral capsule, oral capsule extended release, oral tablet, oral tablet disintegrating
Cardiovascular adverse effects may be associated with phentermine (the active ingredient contained in Adipex-P) Palpitations, tachycardia, elevation of blood pressure, ischemic event have been reported. Primary pulmonary hypertension and valvular heart disease has been reported in patients taking phentermine in combination with fenfluramine or dexfenfluramine and in rare cases in patients who have taken phentermine alone. Analysis of available data suggests that fenfluramine and dexfenfluramine are the causal agents, and both drugs have been withdrawn from the market as of September 15, 1997.
A 37-year-old woman was admitted to the hospital after an episode of ventricular fibrillation. The patient was being treated for moderate obesity and had been taking phentermine hydrochloride, thyroid (USP), and trichlormethiazide. Her previous medical history had been unremarkable. It was suspected that one or more of her medications contributed to the nearly fatal arrhythmia.
Two case reports describe patients using phentermine (one in combination with phendimetrazine) who later developed ischemic cerebrovascular disease. One suffered a cerebral infarct with angiographic evidence of vasculopathy involving multiple vascular beds. The other patient developed headache and a hemisensory disturbance of seven days duration.
A case of fatal pulmonary hypertension has also been reported in a 29-year-old woman 8 months following the use of fenfluramine (of which dexfenfluramine is the dextro isomer) and phentermine for only 23 days. Histopathological findings upon autopsy indicated severe pulmonary hypertension. She did not smoke and had no family history of pulmonary hypertension. No obvious risk factors other than obesity were present, although preexisting disease was not ruled out.
A case of restrictive cardiomyopathy due to endocardial fibrosis after short term use of fenteramine in combination with phentermine has been reported.
Phentermine (the active ingredient contained in Adipex-P) produces nervous system stimulation, which may result in tremor, anxiety, restlessness, dizziness, insomnia, euphoria, dysphoria, and headache.
Fifty women with refractory obesity received phentermine resinate for a period of 20 weeks. Three defaulted from the study due to incapacitating headaches without significant change in blood pressure. Two additional patients defaulted due to complaints of irritability.
A double-blind clinical trial of phentermine and fenfluramine involving 81 people with simple obesity reported several CNS complaints from patients taking phentermine resin during the study (twenty six complaints during the first 6 weeks of the study). The number of complaints diminished with time over the course of the study. Only seven complaints of CNS effects were reported at 20 weeks. Complaints reported by patients include sleep difficulties, nervousness, depression, fatigue and increased dreaming.
Rarely psychotic episodes have been reported at recommended doses with some sympathomimetic drugs.
Gastrointestinal adverse effects may include dryness of the mouth, unpleasant taste, diarrhea, and constipation.
An allergic reaction resulting in urticaria may occur.
Endocrine effects such as impotence and changes in libido may occur in patients taking phentermine (the active ingredient contained in Adipex-P)
More about Adipex-P (phentermine)
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