Fosamprenavir (By mouth)


Fosamprenavir Calcium (fos-am-PREN-a-vir KAL-see-um)

Treats human immunodeficiency virus (HIV) infection. HIV causes acquired immune deficiency syndrome (AIDS). Fosamprenavir does not cure HIV or AIDS, but combinations of drugs may slow the progress of the disease.

Brand Name(s)


There may be other brand names for this medicine.

When This Medicine Should Not Be Used

You should not use this medicine if you have had an allergic reaction to fosamprenavir or amprenavir. Do not use this medicine together with ergot medicines (such as dihydroergotamine, ergonovine, ergotamine, methylergonovine, Cafergot®, DHE 45®, Methergine®, or Migranal®), alfuzosin (Uroxatral®), cisapride (Propulsid®), delavirdine (Rescriptor®), lovastatin (Altocor®, Mevacor®), oral midazolam (Versed®), pimozide (Orap®), rifampin (Rifadin®, Rimactane®), salmeterol (Advair®, Serevent®), sildenafil (Revatio®), simvastatin (Simcor®, Vytorin®, Zocor®), triazolam (Halcion®), or St. John's wort. You should not use flecainide (Tambocor®) or propafenone (Rhythmol®) if you are also using ritonavir (Norvir®) together with this medicine. Do not take this medicine and amprenavir at the same time.

How to Use This Medicine

Liquid, Tablet

  • Your doctor will tell you how much of this medicine to use and how often. Do not use more medicine or use it more often than your doctor tells you to.
  • This medicine comes with patient instructions. Read and follow these instructions carefully. Ask your doctor or pharmacist if you have any questions.
  • You may take this medicine with or without food. Adults should take the oral suspension without food. Children should take the oral suspension with food.
  • Shake the oral suspension well before each use. Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup.
  • Fosamprenavir is used with other medicines to treat HIV infection. Take all other medicines your doctor has prescribed as part of your combination treatment.
  • When your supply of this medicine is running low, contact your doctor or pharmacist ahead of time. Do not allow yourself to run out of this medicine.

If a dose is missed:

  • If you miss a dose or forget to use your medicine and it has been fewer than four hours since you were supposed to take it, use it as soon as you can. If it is almost time for your next dose or it has been longer than 4 hours since you were supposed to take it, wait until your next scheduled time to use the medicine and skip the missed dose.
  • Do not use extra medicine to make up for a missed dose.
  • If you or your child vomits 30 minutes after the first dose, take a second dose right away.

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. The oral suspension may also be refrigerated. Do not freeze.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine away from children and never share your medicine with anyone.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Make sure your doctor knows if you are also using medicine to treat heart rhythm problems (such as amiodarone, bepridil, lidocaine, quinidine, Cardioquin®, Cordarone®, or Vascor®), a blood thinner (such as warfarin, Coumadin®), certain blood pressure medicines (such as amlodipine, diltiazem, felodipine, isradipine, nicardipine, nifedipine, nimodipine, nisoldipine, verapamil, Adalat®, Cardene®, Cardizem®, Covera-HS®, DynaCirc®, Isoptin SR®, Nimotop®, Norvasc®, Plendil®, Procardia®, Sular®, or Tiazac®), or medicine to lower cholesterol (such as atorvastatin, rosuvastatin, Crestor®, or Lipitor®).
  • Tell your doctor if you are also using bosentan (Tracleer®), birth control pills, medicine for seizures (such as carbamazepine, phenobarbital, phenytoin, Dilantin®, Luminal®, or Tegretol®), medicine for depression (such as amitriptyline, imipramine, paroxetine, trazodone, Desyrel®, Elavil®, Paxil®, or Tofranil®), medicine for anxiety (such as alprazolam, clorazepate, diazepam, flurazepam, Dalmane®, Tranxene®, Valium®, or Xanax®), medicine to treat fungus infection (such as itraconazole, ketoconazole, Nizoral®, or Sporanox®), medicine to treat bacteria infection (such as rifabutin, Mycobutin®), a steroid medicine (such as dexamethasone, fluticasone, Decadron®, or Flonase®), a stomach medicine (such as cimetidine, esomeprazole, famotidine, lansoprazole, omeprazole, pantoprazole, rabeprazole, ranitidine, Axid®, Nexium®, Pepcid®, Prevacid®, Prilosec®, Protonix®, Tagamet®, or Zantac®), medicine to treat gout (such as colchicine, Colcrys®), medicine that weakens the immune system (such as cyclosporine, rapamycin or sirolimus, tacrolimus, Gengraf®, Neoral®, Prograf®, Rapamune®, or Sandimmune®), a narcotic pain reliever (such as methadone, Dolophine®), medicine to treat erectile dysfunction (such as sildenafil, tadalafil, vardenafil, Cialis®, Levitra®, or Viagra®), or other medicine to treat HIV or AIDS (such as atazanavir, efavirenz, indinavir, lopinavir/ritonavir, nelfinavir, nevirapine, raltegravir, saquinavir, Crixivan®, Fortovase®, Invirase®, Isentress®, Kaletra®, Reyataz®, Sustiva®, Viracept®, or Viramune®).

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant, or if you have kidney disease, liver disease (especially hepatitis B or C), diabetes, a high amount of cholesterol (fat) in the blood, hemolytic anemia, or hemophilia (a bleeding problem). Your doctor also needs to know if you are allergic to sulfa drugs (sulfonamides) such as Bactrim® or Septra®.
  • You should not breastfeed if you have HIV or AIDS, because you might give the infection to your baby through your breast milk.
  • Serious skin reactions can occur with this medicine. Stop using this medicine and check with your doctor right away if you or your child have blistering, peeling, or loosening of the skin; itching; white spots in the mouth or on the lips; or redness of the skin.
  • When you start taking HIV medicines, your immune system may get stronger. If you have infections that are hidden in your body, such as pneumonia or tuberculosis, you or your child may notice new symptoms when your body tries to fight them. If this occurs, tell your doctor immediately.
  • Birth control pills may not work as well while you are using fosamprenavir. To keep from getting pregnant, use an additional form of birth control with your pills. Other forms include condoms, diaphragms, or contraceptive foams or jellies.
  • This medicine may cause you to have excess body fat. Tell your doctor if you or your child notice changes in your body shape, such as an increased amount of fat in the upper back and neck, or around the chest and stomach area. You might also lose fat from the legs, arms, and face.
  • This medicine may cause blood sugar levels to increase. If you or your child notice a change in the results of your blood or urine sugar tests, or if you have any questions, check with your doctor.
  • Check with your doctor right away if you or your child have any of the following symptoms while using this medicine: itching; skin rash; or swelling of the face, lips, and tongue. You may be having a serious skin reaction or a condition called angioedema.
  • This medicine may increase your cholesterol and fats in the blood. If this condition occurs, your doctor may give you or your child some medicines that can lower the amount of cholesterol and fats in the blood.
  • This medicine may increase your risk of having kidney stones. Stop using this medicine and check with your doctor right away if you or your child have blood in your urine, nausea and vomiting, pain in the groin or genitals, or sharp back pain just below the ribs.
  • Your doctor will need to check your blood at regular visits while you are using this medicine. Be sure to keep all appointments.
  • This medicine will not keep you from giving HIV to your partner during sex. Make sure you understand and practice safe sex, even if your partner also has HIV. Do not share needles with anyone.
  • Make sure any doctor or dentist who treats you knows that you are using this medicine. This medicine may affect the results of certain medical tests.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, or red skin rash.
  • Blood in the urine.
  • Change in how much or how often you urinate, difficult or painful urination.
  • Dark-colored urine or pale stools.
  • Fever, chills, cough, sore throat, and body aches.
  • Increased hunger or thirst, increased urination, or unexplained weight loss.
  • Severe skin rash and itching.
  • Unusual bleeding or bruising.
  • Unusual tiredness or weakness.
  • Yellowing of the skin or the whites of your eyes.

If you notice these less serious side effects, talk with your doctor:

  • Diarrhea, nausea, vomiting, or stomach pain.
  • Gaining weight around your neck, upper back, breast, face, or waist.
  • Headache.
  • Mild skin rash and itching.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last Reviewed on 06/12/2013

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This page was last updated: September 18, 2013

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