Saquinavir is used in combination with ritonavir (another anti-HIV medication) and other anti-HIV (antiretroviral) medications to treat the infection caused by the human immunodeficiency virus (HIV). HIV is the virus responsible for acquired immune deficiency syndrome (AIDS). Saquinavir belongs to a class of medications called protease inhibitors. Saquinavir blocks the action of protease (pronounced "pro-tee-ace"), an enzyme that is needed by HIV to multiply.

This medication does not cure AIDS and does not prevent it from being spread to others. It does slow further growth or reproduction of HIV when used in combination with other medications, and it seems to slow down the destruction of the immune system. This may help to delay the development of problems that are related to AIDS or HIV disease.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

For people 16 years and older, the recommended dose of saquinavir is 1,000 mg taken 2 times a day with food. If you have not taken anti-retroviral medication before, your doctor may suggest that you start with a lower dose and then increase the dose after 1 week. Saquinavir should be swallowed whole with a full glass of water or other non-alcoholic drink. Saquinavir should be taken at the same time as ritonavir, anytime within 2 hours after a meal or large snack. Do not chew or crush this medication.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly  as prescribed. It is most effective when a consistent amount of the medication is in your body. The doses should be spaced as close to every 12 hours as possible. If you miss a dose, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Do not stop taking this medication without telling your doctor. If you miss many doses in a row, talk to your doctor about how to resume taking this medication.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not take saquinavir if you:

• are allergic to saquinavir or any ingredients of the medication
• have a history of problems with the electrical activity of the heart known as QT prolongation
• have a history of problems with electrolyte imbalances (especially low potassium levels in the blood)
• have severe liver problems
• are taking any of the following medications:
• alfuzosin
• atazanavir
• antiarrhythmic medications (e.g., amiodarone, disopyramide, flecainide, procainamide, propafenone, quinidine, sotalol, lidocaine)
• antipsychotic medications (e.g., chlorpromazine, clozapine, haloperidol, lurasidone, pimozide, quetiapine, ziprasidone)
• astemizole
• cisapride
• ergot derivatives
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• midazolam
• quinine
• rifabutin
• rifampin
• rilpivirine
• sildenafil (for pulmonary arterial hypertension)
• "statin" medications (e.g., lovastatin, simvastatin)
• sunitinib
• tacrolimus
• terfenadine
• trazodone
• triazolam

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• diarrhea
• dizziness
• drowsiness
• dry or itchy skin
• gas
• headache
• heartburn
• loss of appetite
• nausea
• tiredness
• vomiting
• weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• abdominal pain
• changes in body fat distribution (increased fat in the upper back and neck, breasts, and trunk; and loss of fat from the arms, legs, and face)
• fainting
• heart rhythm changes, sensation of abnormal heartbeats
• increased cholesterol and triglyceride levels
• lightheadedness
• mouth ulcers
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of pancreatitis (e.g., abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• symptoms of high blood sugar (e.g., frequent urination, increased thirst, excessive eating, unexplained weight loss, poor wound healing, infections, fruity breath odour)
• tingling or numbness
• weight loss

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Abnormal heart rhythm: Saquinavir may cause a problem with the electrical activity of the heart known as QT prolongation, which can affect the heart's rhythm. While you are taking this medication, your doctor will monitor your heart rhythm regularly with a test called an electrocardiogram (ECG). You should not take this medication if your ECG already shows that you have QT prolongation or if you are taking a medication that can cause QT prolongation.

Certain medications (e.g., sotalol, quinidine, thioridazine, chlorpromazine, pimozide, moxifloxacin, mefloquine, pentamidine, arsenic trioxide, tacrolimus) can increase the risk of a type of abnormal heart rhythm called QT prolongation, and should not be used in combination with saquinavir. You are more at risk for this type of abnormal heart rhythm and its complications if you:

• are female
• are older than 65 years of age
• have a family history of sudden cardiac death
• have a history of heart disease or abnormal heart rhythms
• have a slow heart rate
• have congenital prolongation of the QT interval
• have diabetes
• have had a stroke
• have low potassium, magnesium, or calcium levels
• have nutritional deficiencies

If you have heart disease and abnormal heart rhythms, or people are taking certain medications (e.g., verapamil, atazanavir), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Cholesterol: This medication may increase cholesterol or triglyceride (another type of body fat) levels. Your doctor will regularly monitor your cholesterol levels while you are taking saquinavir.

Diabetes: Antiretroviral medications such as saquinavir may increase blood sugar levels. If you have diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is required.

Fat redistribution: Over time, this medication may change how fat is distributed on your body and may change your body shape. With long-term use, you may notice increased fat on the stomach, upper back and neck, chest, stomach area, and breasts. Fat may be reduced on your arms, legs, and face. The long-term effects of this are not known. Notify your doctor if you start developing any changes in your body's appearance.

Foods: Fatty foods and grapefruit juice increase the body's absorption of saquinavir.

Galactose intolerance: Saquinavir medications are prepared with lactose. If you have lactose or galactose intolerance you should not take these medications.

Hemophilia: People with hemophilia may have an increased risk of bleeding while taking this medication. If you have hemophilia, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Immune reconstitution syndrome: This medication may cause immune reconstitution syndrome, where signs and symptoms of inflammation from previous infections appear. These symptoms occur soon after starting anti-HIV medications and can vary. They are thought to occur as a result of the immune system improving and being able to fight infections that have been present without symptoms, such as pneumonia, herpes, or tuberculosis. Report any new symptoms to your doctor immediately.

Liver function: Saquinavir can cause serious liver problems, including liver failure and rarely, death. If you are taking saquinavir, your doctor may request that you have regular liver function tests while you are taking this medication. This medication may also cause a decrease in liver function. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

People with severely impaired liver function should not take saquinavir.

Other medications: Saquinavir may interact with a number of medications, which may mean a change in how you take this medication (See "What medications can interact with this medication?"). Tell your doctor of all medications that you are taking. Certain medications should not be taken with saquinavir at all (see "Who should not take this medication?"). Saquinavir should never be used on its own and should always be used in combination with ritonavir and other HIV medications.

Pancreatitis: Saquinavir can cause the pancreas to become inflamed. If you have a history of pancreatitis, gallstones, alcoholism, or high triglycerides, you may be more at risk of experiencing this. If you have a history of pancreatitis, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Report signs of pancreatitis such as abdominal pain on the upper left side, back pain, nausea, fever, chills, rapid heartbeat, or swollen abdomen to your doctor immediately.

Pregnancy: The medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if saquinavir passes into breast milk. Because HIV can be transmitted by breast milk, breast-feeding is not recommended for women who are HIV-positive.

Children: The safety and effectiveness of using this medication have not been established for children younger than 16 years of age.

There may be an interaction between saquinavir and any of the following:

• abiraterone acetate
• aliskiren
• almotriptan
• alpha blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
• amantadine
• antiarrhythmia medications (e.g., amiodarone, dipyridamole, disopyramide, flecainide, procainamide, propafenone, quinidine, sotalol, lidocaine)
• anti-cancer medications (e.g., cabazitaxel, docetaxel; doxorubicin; etoposide, ifosfamide, irinotecan, vincristine)
• antihistamines (e.g,. cetirizine, doxylamine, diphenhydramine, hydroxyzine, loratadine)
• antimalarial medications (e.g., atovaquone, chloroquine, praziquantil, proguanil)
• antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• apixaban
• apomorphine
• aprepitant
• "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
• benzodiazepines (e.g., chlordiazepoxide, clonazepam, diazepam, lorazepam)
• birth control pills
• bosentan
• brinzolamide
• bromocriptine
• buprenorphine
• buspirone
• busulfan
• calcitriol
• calcium channel blocking agents (e.g., diltiazem, felodipine, amlodipine, verapamil, flunarizine)
• cannabis
• carbamazepine
• carvedilol
• chloral hydrate
• cobicisat
• colchicine
• conivaptan
• corticosteroids for the nose (e.g., fluticasone, mometasone)
• inhaled corticosteroids (e.g., budesonide, ciclesonide, fluticasone)
• oral corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
• cyclosporine
• dabigatran
• daclatasvir
• dantrolene
• dapsone
• darifenacin
• deferasirox
• degarelix
• diabetes medications (e.g., chlorpropamide, glipizide, glyburide, insulin, metformin, rosiglitazone)
• digoxin
• dofetilide
• domperidone
• dronedarone
• enfuvirtide
• enzalutamide
• eplerenone
• ergot alkaloids (e.g., dihydroergotamine, ergonovine, ergotamine, methylergonovine)
• estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
• everolimus
• fesoterodine
• formoterol
• galantamine
• guanfacine
• H2 antagonists (e.g., famotidine, ranitidine)
• hepatitis C antivirals (e.g., simeprevir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delavirdine, efavirenz, etravirine, nevirapine)
• indapamide
• lacosamide
• ledipasvir
• lidocaine
• lithium
• loperamide
• lomitapide
• losartan
• lurasidone
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• macitentan
• maprotiline
• methadone
• netronidazole
• mifepristone
• mirtazapine
• modafinil
• montelukast
• nadolol
• certain narcotics (e.g., fentanyl, hydrocodone, oxycodone)
• nefazodone
• nitrates (e.g., isosorbide dinitrate,  isosorbide mononitrate)
• octreotide
• other HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir)
• oxybutynin
• pentamidine
• perampanel
• phenobarbital
• phenytoin
• phosphodiesterase 5 inhibitors (e.g., avanafil, sildenafil, tadalafil, vardenafil)
• pimecrolimus
• primadone
• progestins (e.g., dienogest, levonorgestrel, medroxyprogesterone, norethindrone)
• proton pump inhibitors (e.g., lansoprazole, omeprazole)
• prucalopride
• protein kinase inhibitors (e.g,. dasatinib, imatinib, nilotinib, sunitinb)
• quinidine
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, norfloxacin, ofloxacin)
• rifabutin
• rifampin
• rilpivirine
• riociguat
• rivaroxaban
• romidepsin
• St. John's wort
• salmeterol
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
• serotonin antagonists (anti-emetic medications; e.g., granisetron, ondansetron)
• siltuximab
• sirolimus
• solifenacin
• "statin" medications (e.g., atorvastatin, lovastatin, simvastatin)
• sulfamethoxazole
• tacrolimus
• tamoxifen
• tetrabenazine
• theophylline
• ticagrelor
• ticlopidine
• tocilizumab
• tolvaptan
• tolterodine
• tramadol
• trazodone
• tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, trimipramine)
• trimethoprim
• ulipristal
• valproic acid
• venlafaxine
• warfarin
• zidovudine
• zolpidem
• zonisamide
• zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.