BRAND INFORMATION
Brand names: Adipex-P, Lomaira, Suprenza
Drug class: S6 – Stimulants
Schedule: S4
Manufacturer: iNova Pharmaceuticals
Molecular Formula: C10H15N
Create Date: 2005-03-25
Modify Date: 2022-07-23
Consumer Medicine Information (CMI) summary
The full CMI on the next page has more details. If you are worried about using this medicine, speak to your doctor or pharmacist.
Contents
What is phentermine? What is it used for?
Phentermine is similar to amphetamine. It stimulates the central nervous system (nerves and brain), which increases your heart rate and blood pressure and decreases your appetite.
Phentermine is used together with diet and exercise to treat obesity, especially in people with risk factors such as high blood pressure, high cholesterol, or diabetes.
Phentermine may also be used for purposes not listed in this medication guide.
Phentermine is most often used for weight loss but may also be used in combination with the medication topiramate to help with certain eating disorders, such as binge eating disorder [1], [2].
Phentermine is an approved weight loss medication by the Therapeutic Goods Administration (TGA) in Australia that is known for its efficacy in reducing weight. Taking phentermine alone or in combination with other drugs may assist in increasing weight loss.
Phentermine belongs to the class of Sympathomimetic Amine Anorectics. The drug works by suppressing appetite and increasing sympathetic activity, resulting in a physiological effect.
Medicines that contain phentermine
Phentermine (GH), Supremine ER, Alenami, Phentodur, Duromine, Metermine.
Warnings
- Do not use phentermine if you are pregnant or breastfeeding a baby.
- You should not use phentermine if you have glaucoma, overactive thyroid, severe heart problems, uncontrolled high blood pressure, advanced coronary artery disease, extreme agitation, or a history of drug abuse.
- Do not use this medicine if you have used a MAO inhibitor in the past 14 days, such as isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, or tranylcypromine. A dangerous drug interaction could occur.
Before taking this medicine
You should not use phentermine if you are allergic to it, or if you have:
✕ a history of heart disease (coronary artery disease, heart rhythm problems, congestive heart failure, stroke);
✕ severe or uncontrolled high blood pressure;
✕ overactive thyroid;
✕ glaucoma;
✕ extreme agitation or nervousness;
✕ a history of drug abuse; or
✕ if you take other diet pills.
Do not use phentermine if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.
Weight loss during pregnancy can harm an unborn baby, even if you are overweight. Do not use phentermine if you are pregnant. Tell your doctor right away if you become pregnant during treatment.
You should not breastfeed while using this medicine.
To make sure this medicine is safe for you, tell your doctor if you have:
✕ heart disease or coronary artery disease;
✕ a heart valve disorder;
✕ high blood pressure;
✕ diabetes (your diabetes medication dose may need to be adjusted); or
✕ kidney disease.
Phentermine is not approved for use by anyone younger than 16 years old.
Contraindications
✕ Known hypersensitivity or idiosyncratic reaction to sympathomimetic amines
✕ History of cardiovascular disease (coronary artery disease, uncontrolled hypertension, arrhythmias, stroke, congestive heart failure)
✕ Glaucoma
✕ Agitated states
✕ Hyperthyroidism
✕ History of drug abuse
✕ Use of monoamine oxidase inhibitors (MAOIs) within the preceding 14 days; concomitant administration of other CNS stimulants
✕ Pregnancy and breastfeeding
Phentermine side effects
Get emergency medical help if you have signs of an allergic reaction to phentermine: hives, difficult breathing, swelling of your face, lips, tongue, or throat.
Phentermine may cause serious side effects. Call your doctor at once if you have:
- feeling short of breath, even with mild exertion;
- chest pain, feeling like you might pass out;
- swelling in your ankles or feet;
- pounding heartbeats or fluttering in your chest;
- tremors, feeling restless, trouble sleeping;
- unusual changes in mood or behaviour; or
- increased blood pressure - severe headache, blurred vision, pounding in your neck or ears, anxiety, nosebleed.
Common side effects of phentermine may include:
- itching;
- dizziness headache;
- dry mouth;
- unpleasant taste;
- diarrhoea;
- constipation;
- stomach pain; or
- increased or decreased interest in sex.
Some of the adverse effects of phentermine may include:
- Heart palpitations
- Raised blood pressure
- A feeling of restlessness
- Headaches
- Dry mouth
- Diarrhoea
- Constipation
- Hives
- A higher or lower libido
This is not a complete list of side effects, and others may occur. Call your doctor for medical advice about side effects. You may report side effects to TGA at 1300 134 237.
How does it work?
Phentermine belongs to a class of drugs called anorectics, also known as appetite suppressants. Taking phentermine helps suppress your appetite, thereby limiting how many calories you eat. Over time, this can lead to weight loss.
While the exact way phentermine reduces appetite remains unclear, the drug is thought to act by increasing neurotransmitter levels in your brain [3], [4].
Neurotransmitters — the chemicals norepinephrine, serotonin, and dopamine — are your body’s chemical messengers [5], [6].
When your levels of these three chemicals increase, your feeling of hunger decreases.
However, you may build a tolerance to the appetite-suppressing effects of phentermine within a few weeks. If that happens, speak with the healthcare professional who prescribed it.
How should I take phentermine?
- Take phentermine exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.
- Doses are normally taken before breakfast or 1 to 2 hours after breakfast. Follow your doctor's dosing instructions very carefully.
- Never use phentermine in larger amounts or for longer than prescribed. Taking more of this medication will not make it more effective and can cause serious, life-threatening side effects.
- This medicine is for short-term use only. The effects of appetite suppression may wear off after a few weeks.
- Phentermine may be habit-forming. Misuse can cause addiction, overdose, or death. Selling or giving away this medicine is against the law.
- Call your doctor at once if you think this medicine is not working as well or if you have not lost at least 4 pounds within 4 weeks.
- Do not stop using this medicine suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to stop using this medicine safely.
- Store at room temperature away from moisture and heat. Keep the bottle tightly closed when not in use.
- To prevent insomnia or difficulty falling or staying asleep, you should avoid taking the last dose too late in the day.
Dosing information
Usual Adult Dose for Obesity:
8 mg orally 3 times a day 30 minutes before meals, OR
15 to 37.5 mg orally once a day before breakfast or 1 to 2 hours after breakfast.
Use: Short-term (a few weeks) adjunct in a regimen of weight reduction based on exercise, behavioural modification, and caloric restriction in the management of exogenous obesity in patients with an initial body mass index (BMI) of 30 kg/m2 or greater, or BMI of 27 kg/m2 or greater in the presence of other risk factors (e.g., controlled hypertension, diabetes, hyperlipidemia).
What happens if I miss a dose?
Take the medicine as soon as possible, but skip the missed dose if it is late in the day. Do not take two doses at one time.
What happens if I overdose?
Overdose symptoms may include confusion, panic, hallucinations, extreme restlessness, nausea, vomiting, diarrhoea, stomach cramps, feeling tired or depressed, irregular heartbeats, weak pulse, seizure, or slow breathing (breathing may stop).
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of phentermine can be fatal.
What to avoid
Avoid driving or hazardous activity until you know how phentermine will affect you. Your reactions could be impaired.
Drinking alcohol with this medicine can cause side effects.
If you’re prescribed a higher dose (15, 30, or 37.5 mg), you can take it once daily in the morning or 1–2 hours after breakfast.
What other drugs will affect phentermine?
Taking phentermine and other diet medications such as fenfluramine (Phen-Fen) or dexfenfluramine (Redux) can cause a rare fatal lung disorder called pulmonary hypertension. Do not take phentermine with any other diet medications without your doctor’s advice.
Many drugs can interact with phentermine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.
What other information should I know?
Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your body’s response to phentermine and topiramate.
Do not let anyone else take your medication. Giving or selling phentermine and topiramate may harm others and is against the law. Phentermine and topiramate are controlled substances. Prescriptions may be refilled only a limited number of times; ask your pharmacist if you have any questions.
You must keep a written list of all the prescription and nonprescription (over-the-counter) medicines you are taking and any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.
References
- Is Phentermine a good option for weight loss? Available from: [URL Link]
- Phentermine HCL – Uses, Side Effects, and More Available from: [URL Link]
- Phentermine. Available from: [URL Link]
- Side effects and precautions. Healthline. Available from: [URL Link]
- Phentermine and Topiramate. Trusted Health Information for you. Available from: [URL Link]
- Phentermine. Related Compounds with Annotation. Pubchem. Available from: [URL Link]
- Phentermine. When and how to use. MedicalNewsToday. Available from: [URL Link]
- Active ingredient: Phentermine. Healthdirect. Available from: [URL Link]
- Phentermine Hydrochloride. PeaceHealth. Available from [URL Link]
Popular FAQ
Exhaustion may happen from restless nights or overstimulation, but phentermine can also cause sleepiness, fatigue, and low energy. If you feel tired or sluggish while taking phentermine, see your doctor. You may have an undetected medical issue.
✓ You have cardiovascular disease
✓ You are taking or recently stopped taking drugs known as monoamine oxidase inhibitors
✓ You have hyperthyroidism
✓ You have glaucoma
✓ You have a history of drug abuse or agitation
✓ You are pregnant or nursing
✓ You are sensitive to or had a reaction to other stimulant drugs
Phentermine is part of a weight-loss programme that typically involves exercise, behaviour modification, and calorie reduction. Phentermine treatment normally lasts 12 weeks. Diet, exercise, and other variables affect phentermine’s weight-loss results.
Phentermine stays 4 days in your system. Half the medicine is gone after 20 hours. Drug elimination depends on several factors. Age, diet, renal and liver health are all contributors.
Doctor-prescribed phentermine use is the best one. It is usually taken first thing in the morning, 1 to 2 hours after breakfast. Phentermine might induce sleeplessness if used at night.
Phentermine affects the brain’s neurotransmitters. It is thought to cause weight loss by suppressing appetite. The exact way phentermine works to cause weight loss is not known. Phentermine belongs to the class of drugs known as sympathomimetic amines. These are more commonly known as stimulant drugs.
Phentermine is a drug approved for weight loss as part of a regimen of exercise, calorie restriction and behaviour modification. Phentermine may be prescribed for short-term treatment in people who have a body mass index (BMI) of 30 kg/m2 or greater. It may also be prescribed to people with a BMI of 27 kg/m2 or greater with other risk factors, such as high blood pressure, diabetes or high cholesterol.
I took it once, and these pills really helped. Probably, I will come back to them soon
Contraindication list was helpful, thanks.
It worked best for me! And it’s so good the drug is in pills. I’m not too fond of needles
Be ready for severe discomfort during the first weeks. I barely survived the side effects. Anyway, no regrets now. I’ve shed 30 pounds!
Once I took two doses instead of a missed one—bad idea. Don’t ever do that.
That alcohol rule is one of the challenging ones. Can’t I even have a glass of wine?