• Basic Info
• Top Questions
• Clinical Info
• Interactions

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.

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.