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 Vemlidy. If you are concerned about side effects, discuss the risks and benefits of Vemlidy with your doctor.

The following side effects have been reported by at least 1% of people taking Vemlidy. 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
• fatigue
• gas
• headache
• nausea
• rash
• 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:

• Hives
• 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)

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)
• signs of lactic acidosis (e.g., nausea, vomiting, increased breathing rate, abdominal pain, unusual tiredness, dizziness, rapid heart rate)

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 Vemlidy.

Each yellow, round, film-coated tablet, debossed with "GSI" on one side and "25" on the other side, contains 25 mg of tenofovir alafenamide (equivalent to 28 mg of tenofovir alafenamide hemifumarate). Nonmedicinal ingredients: croscarmellose sodium, lactose monohydrate, magnesium stearate, and microcrystalline cellulose; film coating: iron oxide yellow, polyethylene glycol, polyvinyl alcohol, talc, and titanium dioxide.

Do not take Vemlidy if you are allergic to tenofovir alafenamide or any ingredients of the medication.

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

• acyclovir
• adefovir
• aminoglycoside antibiotics (e.g., Amikacin, gentamicin, tobramycin)
• Carbamazepine
• cidofovir
• Cladribine
• Cobicistat
• fosphenytoin
• Ganciclovir
• non-steroidal anti-inflammatory medications (NSAIDs; e.g., Diclofenac, Ibuprofen, Naproxen)
• Orlistat
• Oxcarbazepine
• Phenobarbital
• Phenytoin
• primidone
• rifabutin
• rifampin
• St. John's wort
• sofosbuvir
• tipranavir
• Valacyclovir
• valganciclovir

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 Vemlidy. 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 Vemlidy.

Hepatitis B and HIV co-infections: The safety and effectiveness of taking tenofovir alafenamide to treat hepatitis B if you have also have HIV infection has not been determined. If you are taking tenofovir alafenamide for hepatitis B infection and an existing HIV infection is not being treated effectively, tenofovir alafenamide may increase the chance that your HIV infection will not respond to usual treatment. Therefore, it is important to be tested for HIV before starting treatment with tenofovir alafenamide and whenever there is a risk of HIV exposure during treatment.

Kidney function: Vemlidy may affect kidney function. If you have decreased kidney function, discuss with your doctor how Vemlidy may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Vemlidy, and whether any special monitoring is needed.

Lactic acidosis and fatty liver: Vemlidy can cause a rare but serious condition called lactic acidosis (build-up of lactic acid), together with an enlarged fatty liver. Your doctor will periodically monitor you and perform laboratory tests to check your liver function. If you notice any symptoms of this condition such as nausea, vomiting, stomach pain, weakness, tiredness, feeling cold, dizziness, light-headedness, or irregular heartbeat, seek immediate medical attention.

Liver function: Tenofovir alafenamide should not be used if you have significantly decreased or worsening liver function. Report any 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) to your doctor.

Other medications for hepatitis B: There are several combination medications available to treat HIV infection and hepatitis B infection. Many of these medications include tenofovir alafenamide or tenofovir disoproxil. They may also include ingredients that work the same way as the ingredients in Vemlidy. Taking tenofovir alafenamide along with these other medications may be dangerous and may cause fatal drug interactions. With your doctor or pharmacist, review the ingredients of any medication that may be prescribed and compare it to the medications you are currently taking.

Stopping the medication: When used to treat chronic hepatitis B, stopping tenofovir alafenamide has been known to cause symptoms of liver inflammation to flare up and your hepatitis B 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. If you and your doctor decide that you should stop taking tenofovir alafenamide, you will need to have regular blood tests to check liver function and hepatitis B virus levels.

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

Breast-feeding: It is not known if tenofovir alafenamide passes into breast milk. If you are breast-feeding and are taking Vemlidy, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Vemlidy have not been established for children.