Nelfinavir - Dosage | Interactions | Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Nelfinavir is a drug from the group of HIV protease inhibitors - an enzyme that is necessary for the HIV virus to grow and proliferate. By inhibiting this enzyme, Nelfinavir slows down the expansion / replication of the virus and because of such an effect, it is used in patients with AIDS. Nelfinavir is not a cure for AIDS (unfortunately, the cure for AIDS does not exist yet), but it slows down the progression of this disease. Nelfinavir is used in combination with other drugs.

Warnings and precautions

Nelfinavir is contraindicated in the following conditions:

  • Allergy to HIV protease inhibitors.
  • Liver damage.
  • Co-administration with sildenafil (Viagra), tadalafil (Cialis) and other PDE-5 inhibitors.
  • Co-administration with astemizole and terfenadine (antihistamines - drugs for allergy treatment)
  • Co-administration with drugs for malaria treatment (e.g. artemether).
  • Co-administration with corticosteroids (fluticasone, triamcinolone, budesonid, methylprednisolone, prednisone and others).
  • Co-administration with statins, such as: simvastatin (Zocor), atorvastatin (Lipitor), lovastatin, pravastatin, rosuvastatin, and others.
  • Co-administration with drugs for migraine treatment (also called triptans), such as: sumatriptan and eletriptan.

As you can see, Nelfinavir can interact with a large number of drugs, which changes its effects or the effects of other drugs. For this reason, it is very important that your doctor is informed about all the medicines you are taking.

Caution should be exercised in the following situations:

  • Diabetes. There is data that suggests that Nelfinavir can raise blood glucose levels, therefore diabetics must regularly control blood sugar while on treatment with this drug.
  • Renal impairment. Nelfinavir may cause urolithiasis1 and can lead to stone formation in the urinary tract.2 For this reason, it should be used cautiously in patients who already have kidney problems.
  • Blood and circulatory system disorders. HIV protease inhibitors can cause bleeding episodes3, and must be very cautiously applied in patients who already have circulatory disorders.

Nelfinavir, pregnancy and lactation

Nelfinavir is often applied in pregnant women with HIV because it belongs to the group B (according to FDA), which means that there is no proven risk to the fetus. In a study conducted in the Netherlands on 186 pregnant women, it has been proven that some side effects of Nelfinavir are more common in pregnant women than in non-pregnant, as follows:

  • Liver damage
  • Elevated blood glucose level
  • Digestive disorders

The same study, however, states that Nelfinavir is well tolerated during the pregnancy.4

Another study, which included 915 pregnant women, showed that Nelfinavir does not cause embryotoxic effects.5

Your doctor will decide which drug you should take for AIDS treatment during pregnancy.

Do not breastfeed while taking Nelfinavir.


According to the recommendations of the US CDC, Nelfinavir should be taken in a dose of 1250 mg every 12 hours or 750 mg every 8 hours, for four weeks.

It can also be used in patients who aren't HIV positive but have been exposed to the virus and are at increased risk for getting the disease. For this purpose, Nelfinavir must be taken within three days of virus exposure.

It also exists in the form of syrups which are intended for use in children. The pediatrician will determine what dose is suitable for the child.

Take the pill after a meal with plenty of fluids.


You can see interactions in the section, Precautions.

Note: Nelfinavir interacts with a large number of drugs (about 2500 drugs), and you need to tell your doctor about all the medications you are taking. There is a great chance that Nelfinavir will interact with some drug you're already taking. The interaction between the drugs can be very dangerous!

Adverse effects

The most dangerous side effect of this drug is an allergic reaction that can cause difficulty in breathing. Tell your doctor if you notice any symptoms of an allergy.

You must immediately inform your doctor if you notice some of the following side effects:

  • Signs of infection (sore throat, cough and chills)
  • Bleeding
  • Hyperglycemia (increased thirst, increased hunger, changed breath odor, confusion and drowsiness)

Other side effects of Nelfinavir are:

  • Arrhythmias
  • Pain and tightness in the chest
  • Pain and cramping in the stomach
  • Vomiting blood
  • Loss of appetite and weight loss
  • Digestive disorders
  • Drowsiness


  1. NCBI link 1
  2. NCBI link 2
  3. NCBI link 3
  4. NCBI link 4
  5. NCBI link 5

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.

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