Nelfinavir can cause serious, life-threatening side effects. These include liver problems in people with moderate or severe liver impairment and life-threatening drug interactions.
The artificial sweetener (aspartame) in nelfinavir oral powder contains phenylalanine. Phenylalanine may be harmful to people with PKU.
While taking nelfinavir, it is important to keep all of your appointments with your health care provider.
Nelfinavir is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV infection in children 2 years of age and older and adults. Nelfinavir is always used in combination with other HIV medicines.
Nelfinavir belongs to a class (group) of HIV drugs called protease inhibitors (PIs). PIs block an HIV enzyme called protease. (An enzyme is a protein that starts or increases the speed of a chemical reaction.) By blocking protease, PIs prevent HIV from multiplying and can reduce the amount of HIV in the body.
HIV medicines can’t cure HIV/AIDS, but taking a combination of HIV medicines (called an HIV regimen) every day helps people with HIV live longer, healthier lives. HIV medicines also reduce the risk of HIV transmission. If you are taking HIV medicines, including nelfinavir, don’t cut down on, skip, or stop taking them unless your health care provider tells you to.
Before taking nelfinavir, tell your health care provider:
Nelfinavir (brand name: Viracept) comes in the following forms and strengths:
Take nelfinavir according to your health care provider’s instructions.
Nelfinavir tablets should always be taken with a meal. If you or your child has trouble with swallowing the tablets, you can dissolve the tablets in a small amount of water. Once the tablets are dissolved, the liquid will be cloudy. Mix the cloudy liquid well and drink immediately. The glass should be rinsed with water, and then the rinse should be swallowed.
Nelfinavir oral powder is another option for people who have trouble with swallowing nelfinavir tablets. The oral powder may be mixed with a small amount of water, milk, formula, soy formula, soy milk, or liquid dietary supplements. Do not mix oral powder in the container that it comes in. Do not mix the powder with any acidic food or juice. Once mixed, the entire dose of nelfinavir must be taken. If the mixture is not taken immediately, it must be stored in the refrigerator, but not for longer than 6 hours.
If you are also taking the HIV medicine didanosine (brand names: Videx; Videx EC), take nelfinavir with food 1 hour after or more than 2 hours before you take didanosine.
Always take nelfinavir in combination with other HIV medicines.
If you take too much nelfinavir, contact your health care provider or local poison control center (1-800-222-1222) right away, or go to the nearest hospital emergency room.
For more information on how to take nelfinavir, see the FDA drug label from DailyMed. (DailyMed is a federal website that includes the most recent drug labels submitted to FDA.)
If you miss a dose of nelfinavir, take the missed dose as soon as you remember it. But if it is almost time for your next dose, skip the missed dose and just take your next dose at the regular time. Do not take two doses at the same time to make up for a missed dose.
Nelfinavir may cause side effects. Most side effects from nelfinavir are manageable, but a few can be serious. Serious side effects of nelfinavir include liver problems in people with moderate or severe liver impairment and life-threatening drug interactions. The artificial sweetener (aspartame) in nelfinavir oral powder contains phenylalanine. Phenylalanine may be harmful to people with PKU. (See the WARNING above.)
Other possible side effects of nelfinavir include:
Tell your health care provider if you have any side effect that bothers you or that does not go away.
These are not all the possible side effects of nelfinavir. To learn more about possible side effects of nelfinavir, read the drug label or package insert or talk to your health care provider or pharmacist.
The AIDSinfo fact sheet on HIV Medicines and Side Effects also includes information that may apply to nelfinavir.
You can also report side effects to FDA at 1-800-FDA-1088 (1-800-332-1088) or online at https://www.accessdata.fda.gov/scripts/medwatch/.
More information about nelfinavir is available:
Last Reviewed: December 17, 2015