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Generic name: nelfinavir (nel FIN a veer)
Brand name: Viracept
Dosage forms: oral tablet (250 mg; 625 mg)
Drug class: Protease inhibitors

Medically reviewed by on May 3, 2021. Written by Cerner Multum.

What is nelfinavir?

Nelfinavir is an antiviral medicine that prevents human immunodeficiency virus (HIV) from multiplying in your body.

Nelfinavir is used to treat HIV, the virus that can cause acquired immunodeficiency syndrome (AIDS). Nelfinavir is not a cure for HIV or AIDS.

Nelfinavir may also be used for purposes not listed in this medication guide.


You should not use nelfinavir if you have moderate to severe liver disease.

Serious drug interactions can occur when certain medicines are used together with nelfinavir. Tell each of your healthcare providers about all medicines you use now, and any medicine you start or stop using.

Before taking this medicine

You should not take this medication if you are allergic to nelfinavir, or if you have moderate or severe liver disease.

Some medicines can cause unwanted or dangerous effects when used with nelfinavir. Your doctor may need to change your treatment plan if you use any of the following drugs:

To make sure nelfinavir is safe for you, tell your doctor if you have:

  • liver disease;

  • kidney disease;

  • diabetes;

  • a bleeding disorder such as hemophilia; or

  • high cholesterol or triglycerides.

This medication is not expected to be harmful to an unborn baby, but HIV can be passed to your baby if you are not properly treated during pregnancy. Tell your doctor if you are pregnant or plan to become pregnant. Take all of your HIV medicines as directed to control your infection.

If you are pregnant, your name may be listed on a pregnancy registry. This is to track the outcome of the pregnancy and to evaluate any effects of nelfinavir on the baby.

Nelfinavir can make birth control pills less effective. Ask your doctor about using non hormonal birth control (condom, diaphragm with spermicide) to prevent pregnancy.

You should not breast-feed while you are using nelfinavir. Women with HIV or AIDS should not breast-feed at all. Even if your baby is born without HIV, you may still pass the virus to the baby in your breast milk.

Nelfinavir is not approved for use by anyone younger than 2 years old.

How should I take nelfinavir?

Follow all directions on your prescription label. Do not take nelfinavir in larger or smaller amounts or for longer than recommended.

Read all patient information, medication guides, and instruction sheets provided to you. Ask your doctor or pharmacist if you have any questions.

Nelfinavir works best if you take it with food.

Swallow the nelfinavir tablet whole.

If you cannot swallow a whole tablet, dissolve it in a small amount of water. Stir this mixture and drink all of it right away. To make sure you get the entire dose, add a little more water to the same glass, swirl gently and drink right away.

If a child is using this medicine, tell your doctor if the child has any changes in weight. Nelfinavir doses are based on weight in children, and any changes may affect your child's dose.

Use nelfinavir regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely.

HIV/AIDS is usually treated with a combination of drugs. Use all medications as directed by your doctor. Read the medication guide or patient instructions provided with each medication. Do not change your doses or medication schedule without your doctor's advice. Every person with HIV or AIDS should remain under the care of a doctor.

While using nelfinavir, you may need frequent blood tests.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking nelfinavir?

If you also take didanosine, take it 1 hour before or 2 hours after you take nelfinavir.

Taking nelfinavir will not prevent you from passing HIV to other people. Do not have unprotected sex or share razors or toothbrushes. Talk with your doctor about safe ways to prevent HIV transmission during sex. Sharing drug or medicine needles is never safe, even for a healthy person.

Nelfinavir side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin; or

  • high blood sugar--increased thirst, increased urination, hunger, dry mouth, fruity breath odor, drowsiness, dry skin, blurred vision, weight loss.

Nelfinavir may increase your risk of certain infections or autoimmune disorders by changing the way your immune system works. Symptoms may occur weeks or months after you start treatment with nelfinavir. Tell your doctor if you have:

  • signs of a new infection--fever, night sweats, swollen glands, mouth sores, diarrhea, stomach pain, weight loss;

  • chest pain (especially when you breathe), dry cough, wheezing, feeling short of breath;

  • cold sores, sores on your genital or anal area;

  • rapid heart rate, feeling anxious or irritable, weakness or prickly feeling, problems with balance or eye movement;

  • trouble speaking or swallowing, severe lower back pain, loss of bladder or bowel control; or

  • swelling in your neck or throat (enlarged thyroid), menstrual changes, impotence, loss of interest in sex.

Common side effects may include:

  • infections;

  • nausea, diarrhea, gas, stomach pain;

  • loss of appetite;

  • rash; or

  • changes in the shape or location of body fat (especially in your arms, legs, face, neck, breasts, and waist).

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 FDA at 1-800-FDA-1088.

Nelfinavir dosing information

Usual Adult Dose for HIV Infection:

1250 mg orally twice a day or 750 mg orally 3 times a day

Use: In combination with other antiretroviral agents, for the treatment of HIV-1 infection

Usual Adult Dose for Nonoccupational Exposure:

US CDC recommendations: 1250 mg orally twice a day or 750 mg orally 3 times a day
Duration of therapy: 28 days

-Recommended as part of an alternative regimen for nonoccupational postexposure prophylaxis of HIV infection
-This drug should be used with (lamivudine or emtricitabine) plus (zidovudine or stavudine or abacavir or tenofovir or didanosine).
-Prophylaxis should be started as soon as possible, within 72 hours of exposure.
-Current guidelines should be consulted for additional information.

Usual Pediatric Dose for HIV Infection:

2 to less than 13 years: 45 to 55 mg/kg orally twice a day or 25 to 35 mg/kg orally 3 times a day
Maximum dose: 2500 mg/day

-Oral powder (50 mg/g):
9 to less than 10.5 kg: 500 mg orally twice a day or 300 mg orally 3 times a day
10.5 to less than 12 kg: 550 mg orally twice a day or 350 mg orally 3 times a day
12 to less than 14 kg: 650 mg orally twice a day or 400 mg orally 3 times a day
14 to less than 16 kg: 750 mg orally twice a day or 450 mg orally 3 times a day
16 to less than 18 kg: 500 mg orally 3 times a day
18 to less than 23 kg: 600 mg orally 3 times a day
23 kg or more: 750 mg orally 3 times a day

-Tablets (250 mg):
10 to 12 kg: 500 mg orally twice a day or 250 mg orally 3 times a day
13 to 18 kg: 750 mg orally twice a day or 500 mg orally 3 times a day
19 to 20 kg: 1000 mg orally twice a day or 500 mg orally 3 times a day
21 kg or more: 1000 to 1250 mg orally twice a day or 750 mg orally 3 times a day

13 years or older:
-Tablets: 1250 mg orally twice a day or 750 mg orally 3 times a day

Comments: For twice-daily dosing, the 250 mg tablets are recommended for children weighing 16 kg or more.

Use: In combination with other antiretroviral agents, for the treatment of HIV-1 infection

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What other drugs will affect nelfinavir?

Many drugs can interact with nelfinavir. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any you start or stop using, especially:

This list is not complete and many other drugs can interact with nelfinavir. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Give a list of all your medicines to any healthcare provider who treats you.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.