Taking phentermine together with 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.
Phentermine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.
Avoid drinking alcohol. It can increase some of the side effects of phentermine.
Phentermine may be habit-forming and should be used only by the person it was prescribed for. Keep track of how many pills have been used from each new bottle of this medicine. Phentermine is a drug of abuse and you should be aware if any person in the household is using this medicine improperly or without a prescription.
You may have withdrawal symptoms, such as depression and extreme tiredness, when you stop using phentermine after a long period of use. Do not stop using phentermine suddenly without first talking to your doctor. You may need to use less and less before you stop the medication completely.
Phentermine is a stimulant that is similar to an amphetamine. Phentermine is an appetite suppressant that affects the central nervous system.
Phentermine is used togther with diet and exercise to treat obesity (overweight) in people with risk factors such as high blood pressure, high cholesterol, or diabetes.
Phentermine may also be used for other purposes not listed in this medication guide.
Do not take phentermine if you have used an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), or tranylcypromine (Parnate) within the past 14 days. Serious, life-threatening side effects can occur if you take phentermine before the MAO inhibitor has cleared from your body.
Taking phentermine together with 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.
Do not take this medication if you are allergic to phentermine or other stimulants, or if you have:
heart disease or high blood pressure;
arteriosclerosis (hardening of the arteries);
an overactive thyroid;
glaucoma;
if you are in an agitated state; or
if you have a history of drug or alcohol abuse.
Before taking phentermine, tell your doctor if you are allergic to any drugs, or if you have:
a thyroid disorder;
anxiety disorder;
diabetes; or
epilepsy or another seizure disorder.
If you have any of these conditions, you may need a dose adjustment or special tests during treatment.
It is not known whether phentermine will harm an unborn baby. Do not take phentermine without telling your doctor if you are pregnant.
It is also not known whether phentermine passes into breast milk or if it could harm a nursing baby. Do not take phentermine without telling your doctor if you are breast-feeding a baby.
Do not give this medication to anyone younger than 16 years old without the advice of a doctor.
Phentermine may be habit-forming and should be used only by the person it was prescribed for. Phentermine should never be shared with another person, especially someone who has a history of drug abuse or addiction. Keep the medication in a secure place where others cannot get to it.
Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.
It is best to take phentermine on an empty stomach before breakfast, or at least 10 to 14 hours before bedtime.
Do not take more phentermine for an increased effect. Taking too much of this medication can cause serious, life-threatening side effects.
Do not crush, chew, break, or open an extended-release capsule. Swallow the pill whole. It is specially made to release medicine slowly in the body. Breaking or opening the pill would cause too much of the drug to be released at one time.
Phentermine should be taken only for a short time, such as a few weeks.
Taking high doses of phentermine over long periods of time can cause severe skin problems, sleep problems (insomnia), personality changes, and feeling hyperactive or irritable.
Stop taking phentermine if you have increased hunger or if you otherwise think the medication is not working properly.
You may have withdrawal symptoms when you stop using phentermine after a long period of use. Do not stop using the medication suddenly without first talking to your doctor. You may need to use less and less before you stop the medication completely.
Do not take phentermine in the evening because it may cause sleep problems (insomnia).
Store this medication at room temperature away from moisture and heat.
Keep track of how many pills have been used from each new bottle of this medicine. Phentermine is a drug of abuse and you should be aware if any person in the household is using this medicine improperly or without a prescription.
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at your next regularly scheduled time. Do not take extra medicine to make up the missed dose.
Avoid drinking alcohol. It can increase some of the side effects of phentermine.
Phentermine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert.
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Stop using phentermine and call your doctor at once if you have any of these serious side effects:
feeling short of breath, even with mild exertion;
swelling, rapid weight gain;
chest pain, fast or uneven heartbeat, feeling like you might pass out;
unusual thoughts or behavior, feeling restless or confused; or
dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, confusion, chest pain, shortness of breath, uneven heartbeats, seizure).
Less serious side effects may include:
feeling nervous or anxious;
headache, dizziness, tremors;
trouble sleeping (insomnia);
dry mouth or an unpleasant taste in your mouth;
diarrhea or constipation; or
itching.
This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect.
Before taking phentermine, tell your doctor if you are using any of the following drugs:
medicines to treat high blood pressure;
insulin or diabetes medication you take by mouth;
guanadrel (Hylorel), guanethidine (Ismelin);
antidepressants such as citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac, Sarafem), fluvoxamine (Luvox), paroxetine (Paxil), or sertraline (Zoloft); or
antidepressants such as amitriptyline (Elavil, Etrafon), amoxapine (Ascendin), clomipramine (Anafranil), desipramine (Norpramin), doxepin (Sinequan), imipramine (Janimine, Tofranil), nortriptyline (Pamelor), protriptyline (Vivactil), or trimipramine (Surmontil).
This list is not complete and there may be other drugs that can interact with phentermine. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.
Your pharmacist can provide more information about phentermine.
This information does not replace the advice of a doctor. Healthwise disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.
Your use of the content provided in this service indicates that you have read, understood and agree to the End-User License Agreement. Access the agreement.
