Foscarnet may seriously damage renal function. Dehydrated individuals are more likely to suffer renal injury. To determine whether this drug has an impact on your kidneys, your doctor will request laboratory testing both before and throughout your therapy. Inform your doctor if you have renal disease, have ever had kidney disease, have dry mouth, dark urine, decreased sweating, dry skin, or any other symptoms of dehydration. Also mention any recent episodes of diarrhoea, vomiting, fever, infection, excessive sweating, or dehydration.Inform your doctor and pharmacist if you’re taking acyclovir (Zovirax), amphotericin (Abelcet, Ambisome), cyclosporine (Gengraf, Neoral, Sandimmune), methotrexate (Otrexup, Rasuvo, Trexall), pentamidine (Nebupent, Pentam), tacrolimus (Astagraf, Prograf), or any other medications. It’s possible that your doctor will advise against getting a foscarnet injection. Call your doctor right away if you have any of the following signs or symptoms: reduced urination, facial, arm, hand, foot, ankle, or lower leg edema; unusual fatigue; or weakness.

Keep all of your doctor’s appointments, including those with your eye doctor and the lab. Before and throughout your therapy, your doctor will order specific tests to monitor how your body is reacting to foscarnet, including regular eye exams. A pre- and post-treatment electrocardiogram (ECG), a test that monitors the electrical activity in the heart, may also be prescribed by your doctor.

Keep all of your doctor’s appointments, including those with your eye doctor and the lab. Before and throughout your therapy, your doctor will order specific tests to monitor how your body is reacting to foscarnet, including regular eye exams. A pre- and post-treatment electrocardiogram (ECG), a test that monitors the electrical activity in the heart, may also be prescribed by your doctor.

Foscarnet injection is used alone or with ganciclovir (Cytovene) to treat cytomegalovirus (CMV) retinitis (an eye infection that can cause blindness) in people who have human immunodeficiency virus (HIV) infection. Foscarnet injection is also used to treat herpes simplex virus (HSV) infections of the skin and mucus membranes (mouth, anus) in people whose immune system is not working normally and when treatment with acyclovir did not help. Foscarnet is in a class of medications called antivirals. It works by slowing the growth of CMV and HSV. Foscarnet controls CMV retinitis and HSV infections of the skin and mucus membranes but does not cure these infections.

The liquid form of the foscarnet injection is administered intravenously (into a vein). Every 8 or 12 hours, it is typically slowly administered over 1 to 2 hours. Your response to the drug will determine how long you need to receive treatment.

The injection of foscarnet may be administered at home or in a medical facility. Your healthcare practitioner will demonstrate how to administer the drug if you will be receiving foscarnet injection at home. Make sure you comprehend these instructions, and if you have any concerns, consult your healthcare practitioner.

For a copy of the manufacturer’s information for the patient, ask your pharmacist or doctor.

Patients who have HIV may occasionally receive a foscarnet injection to treat and prevent CMV infections. The dangers of using this drug for your illness should be discussed with your doctor.

Ask your doctor or pharmacist for more details if you believe this drug should be used for something else.

Before using foscarnet injection,

• If you have an allergy to foscarnet, any other drugs, or any of the ingredients in foscarnet injection, let your doctor and pharmacist know right away. Request a list of the components from your pharmacist.
• Inform your doctor and pharmacist about any additional prescription and over-the-counter drugs, vitamins, dietary supplements, and herbal products you are now taking or intend to use. Mention the drugs in the IMPORTANT WARNING section as well as any of the following: azithromycin (Zithromax), clarithromycin (Biaxin), amiodarone (Cordarone, Nexterone, Pacerone), bumetanide, ethacrynic acid (Edecrin), furosemide (Lasix), or torsemide (Demadex), as well as dofetilide (Tikosyn), are diuretics (often known as “water pills”); fluoroquinolone drugs such as ciprofloxacin (Cipro), gatifloxacin (Tequin), levofloxacin (Levaquin), moxifloxacin (Avelox), and ofloxacin (Floxin); erythromycin (E-mycin, Ery-Tab, among others); procainamide; quinidine (in Nuedexta); ritonavir (in Norvir, in Kaletra); saquinavir (in Invirase); sotalol (in Betapace, Sorine); drugs for nausea or mental disease; as well as tricyclic antidepressants (often referred to as “mood elevators”) as amitriptyline, desipramine (Norpramin), doxepin (Silenor), or nortriptyline (Pamelor). Your doctor might need to adjust your medication doses or keep a close eye out for any negative side effects. Inform your doctor about all the drugs you are taking, even those not on this list, as many other drugs may also interact with foscarnet injection.
• Inform your doctor if you have or have ever had QT prolongation, low blood potassium or magnesium levels, heart disease, or are following a low-sodium diet. QT prolongation is an abnormal heart rhythm that can cause fainting, loss of consciousness, seizures, or sudden death.
• Inform your physician if you are nursing a baby, intend to get pregnant, or are already pregnant. Call your doctor if you conceive while receiving a foscarnet injection.
• You should be aware that taking foscarnet may cause you to feel sleepy or lightheaded. Prior to understanding how this drug affects you, avoid using machinery or driving a car.

Keep eating normally unless your doctor instructs you otherwise.

Foscarnet could have negative effects. If any of these symptoms are severe or do not go away, let your doctor know right once:

• Itching, redness, discomfort, or swelling where you had your injection
• Nausea
• Abdominal pain
• Back ache
• Appetite loss or weight loss
• Constipation
• Headache
• Vision alterations
• Penis redness, inflammation, or sores
• Vaginal area rashes, discomfort, or soreness

Some adverse effects can be very harmful. Call your doctor right away or seek emergency medical attention if you develop any of these signs or any of the ones detailed in the IMPORTANT WARNING section:

• Rash
• Hives
• Enlargement of the throat, lips, tongue, eyes, or face
• Breathing or swallowing challenges
• Chest ache
• Hammering, rapid, or erratic heartbeat
• Fainting
• Lightheadedness
• Consciousness is lost
• Vomiting
• Diarrhea
• Fever, chills, cough, or other infection-related symptoms
• Uncommon bruising or bleeding
• Stool that is dark and tarry
• Vomit that has blood in it or looks like coffee grounds
• Light skin
• Breathing difficulty
• Confusion
• Cramping or aching muscles
• Increased perspiration

Other negative effects of foscarnet are possible. If you experience any strange issues while taking this drug, call your doctor right away.

You or your doctor can submit a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online at http://www.fda.gov/Safety/MedWatch or by phone at 1-800-332-1088 if you have a serious side event.

Call 1-800-222-1222 to reach the poison control hotline in the event of an overdose. You can get information online at https://www.poisonhelp.org/help. Call emergency services at 911 right away if the sufferer has fallen, experienced a seizure, is having problems breathing, or cannot be roused.

The following are examples of overdose symptoms:

• Seizures
• Tingling or numbness in the fingers, toes, or mouth
• Less urinations
• Edema of the lower legs, lower arms, hands, feet, ankles, or face
• Unexpected fatigue or weakened state

You should keep a written record of every medication you take, including any over-the-counter (OTC) items, prescription drugs, and dietary supplements like vitamins and minerals. This list should be brought with you whenever you see a doctor or are admitted to the hospital. You should always have this information with you in case of emergencies.