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 RUKOBIA (Fostemsavir). If you are concerned about side effects, discuss the risks and benefits of RUKOBIA (Fostemsavir) with your doctor.

The following side effects have been reported by at least 1% of people taking RUKOBIA (Fostemsavir). 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.

• abdominal pain
• Diarrhea
• dizziness
• headache
• indigestion
• itching
• lack of energy
• muscle aches
• nausea
• rash
• sleepiness
• taste disturbance
• trouble sleeping
• unusual weakness
• vomiting

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:

• 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)
• symptoms of immune reconstitution inflammatory syndrome (e.g., Fever, redness, rash or swelling, fatigue, joint or muscle pain, numbness or weakness in the extremities, pounding heartbeat, chest pain)
• symptoms of irregular heartbeat (e.g., chest pain, dizziness, rapid, pounding heartbeat, shortness of breath)
• tingling, numbness, or weakness in the hands and/or feet

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 RUKOBIA (Fostemsavir).

Each beige, biconvex, oval, film-coated, extended-release tablet, debossed with "SV 1V7" on one side and plain on the other side, contains 600 mg of RUKOBIA (Fostemsavir) (as 724.56 mg of RUKOBIA (Fostemsavir) tromethamine). Nonmedicinal ingredients: colloidal silicon dioxide, hydroxypropyl cellulose, hypromellose, iron oxide red, iron oxide yellow, magnesium stearate, polyethylene glycol, polyvinyl alcohol, talc, and titanium dioxide.

Do not take RUKOBIA (Fostemsavir) if you: 

• are allergic to RUKOBIA (Fostemsavir) or any ingredients of the medication
• are taking any of the following medications:
• carbamazepine
• enzalutamide
• fosphenytoin
• mitotane
• phenobarbital
• phenytoin
• primidone
• rifampin
• St. John's wort

There may be an interaction between RUKOBIA (Fostemsavir) and any of the following:

• anti-arrhythmic medications (e.g., amiodarone, disopyramide, dronedarone, procainamide, quinidine, sotalol)
• apalutamide
• chlorpromazine
• cladribine
• elagolix
• enzalutamide
• ethinyl estradiol
• haloperidol
• hepatitis C antivirals (e.g., glecaprevir, grazoprevir, ledipasvir, velpatasvir, voxilaprevir)
• HIV protease inhibitors (e.g., atazanavir, darunavir, ritonavir)
• methadone
• mitotane
• protein kinase inhibitors (e.g., alpelisib, pazopanib, vandetanib)
• quinine
• rifabutin
• rifampin
• St. John's wort
• seizure medications (e.g., carbamazepine, phenobarbital, phenytoin, primidone)
• "statin" anti-cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
• topotecan
• ziprasidone

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 RUKOBIA (Fostemsavir). 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.

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 RUKOBIA (Fostemsavir).

Heart rhythm: RUKOBIA (Fostemsavir) can cause changes to the normal rhythm of the heart, including an irregular heartbeat called QT prolongation, when more than the recommended dose is taken. QT prolongation is a serious life-threatening condition that can cause fainting, seizures, and sudden death.

People with heart failure, Angina, low potassium or magnesium levels, or those who are taking other medications that can cause changes to the heart rhythm, may be at risk of developing an irregular heartbeat. If you have heart problems, or you are taking other medications, discuss with your doctor how RUKOBIA (Fostemsavir) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of RUKOBIA (Fostemsavir), and whether any special monitoring is needed.

Hepatitis B and C: People who have hepatitis B or Hepatitis C may be more likely to experience decreased liver function and side effects involving the liver when they are taking RUKOBIA (Fostemsavir). If you have hepatitis B or C, discuss with your doctor how RUKOBIA (Fostemsavir) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of RUKOBIA (Fostemsavir), and whether any special monitoring is needed.

Immune reconstitution inflammatory syndrome: RUKOBIA (Fostemsavir) may cause immune reconstitution syndrome, where signs and symptoms of inflammation from previous infections appear. These symptoms occur soon after starting anti-HIV medication and can vary. They are thought to occur because 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.

Stopping the medication: If you stop taking RUKOBIA (Fostemsavir), your HIV infection could get worse. Take the medication exactly as prescribed by your doctor and do not stop taking the medication without checking with your doctor first.

Pregnancy: RUKOBIA (Fostemsavir) should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking RUKOBIA (Fostemsavir), contact your doctor immediately.

Breast-feeding: It is not known if RUKOBIA (Fostemsavir) passes into breast milk.Women with HIV infection are cautioned against breast-feeding because of the risk of passing HIV to a baby who does not have the infection, since the virus can be transmitted through breast milk.

Children: The safety and effectiveness of using RUKOBIA (Fostemsavir) have not been established for children.