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.
Bone health: Tenofovir may reduce bone mineral density and should not be taken by anyone who is at risk for bone problems. If you have osteoporosis, 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. If you experience bone pain or a bone fracture while taking this medication, contact your doctor. Your doctor may do tests to monitor the effect of tenofovir on your bones.
Fat redistribution: Over time, this medication may change how fat is distributed in your body and may change your body shape. You may notice increased fat in the upper back and neck, breast, around the back, chest, and stomach area; or loss of fat from the legs, arms, and face. The long-term effects of this are not known.
HIV and hepatitis B co-infections: If you are taking tenofovir for hepatitis B infection and you get or have HIV infection and are not taking medication to treat HIV, tenofovir 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 and whenever there is a risk of HIV exposure during treatment.
Immune reconstitution syndrome: When you start taking tenofovir, your immune system may get stronger and start to fight other infections that have been hidden in your body (e.g., pneumonia, herpes, or tuberculosis). Contact your doctor if you develop any new symptoms after starting tenofovir. Report any signs of infection such as fever, chills, shortness of breath, cough, or rapid weight loss to your doctor immediately.
Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing increased side effects. If you have kidney disease or reduced kidney function, 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. Tenofovir can cause kidney problems, including severe kidney damage and kidney failure. Your doctor may monitor your kidney function with blood tests while you are taking this medication. Additional tests may be needed if you have a history of kidney problems or if you need to take another medication that can cause kidney problems. Your doctor may also need to change the dosing schedule of this medication if you have existing kidney problems.
Lactic acidosis and enlarged liver: This medication can cause a rare but serious condition called lactic acidosis (buildup 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, lightheadedness, or irregular heartbeat, seek immediate medical attention.
Liver: Tenofovir can cause liver problems. If you have liver disease, 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. Your doctor may monitor your liver function with blood tests while you are taking tenofovir, especially if you have risk factors for liver problems. 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.
Pancreatitis: Tenofovir may cause inflammation of the pancreas (pancreatitis). If you have a history of, or are at risk for developing, 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. If you develop signs of pancreatitis (e.g., upper left abdominal pain, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen), contact your doctor.
Stopping the medication: When used to treat chronic hepatitis B, stopping tenofovir 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, you will need to have regular blood tests to check liver function and hepatitis B virus levels.
Pregnancy: This 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 tenofovir passes into breast milk. Women who have HIV infection are cautioned against breast-feeding because of the risk of passing HIV to a baby who does not have the infection.
Children: For the treatment of HIV infection, the safety and effectiveness of this medication have not been established for children less than 12 years old. For the treatment of chronic hepatitis B infection, the safety and effectiveness of this medication have not been established for children less than 18 years old.