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

The following side effects have been reported by at least 1% of people taking Zerit. 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.

• chills
• cough
• Diarrhea
• difficulty sleeping
• dizziness
• dry skin
• Fever
• gas
• headache
• lack of strength or energy
• loss of appetite
• nausea
• skin rash
• sore throat
• stomach pain (mild)
• vomiting

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

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

• joint pain
• muscle pain
• signs of liver toxicity (e.g., yellowing of skin and eyes, dark urine, light-coloured bowel movements)
• stomach pain (severe)
• symptoms of Depression (e.g., losing interest in your usual activities, feeling sad)
• symptoms of pancreatitis (upper left abdominal pain, back pain, nausea, fever, chills, rapid heartbeat, swollen abdomen)
• tingling, burning, numbness, or pain in the hands or feet
• unusual tiredness or weakness
• weight loss

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

• signs of lactic acidosis (e.g., dizziness, fatigue, unusual muscle pain, nausea, vomiting, stomach pain, feeling cold in legs and arms, fast heartbeat)
• signs of a serious allergic reaction (i.e., abdominal cramps, difficulty breathing, nausea and vomiting , sweating, fast heartbeat, 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 Zerit.

15 mg
Each light-yellow and dark-red capsule marked "BMS 1964" and "15" contains 15 mg of stavudine. Nonmedicinal ingredients: lactose, magnesium stearate, microcrystalline cellulose, and sodium starch glycolate; capsule shell: gelatin, printing ink, silicon dioxide, sodium lauryl sulphate, titanium dioxide, and yellow and red iron oxides.

20 mg
Each light-brown capsule marked "BMS 1965" and "20" contains 20 mg of stavudine. Nonmedicinal ingredients: lactose, magnesium stearate, microcrystalline cellulose, and sodium starch glycolate; capsule shell: gelatin, printing ink, silicon dioxide, sodium lauryl sulphate, titanium dioxide, and yellow, red, and black iron oxide.

30 mg
Each light-orange and dark-orange capsule marked "BMS 1966" and "30" contains 30 mg of stavudine. Nonmedicinal ingredients: lactose, magnesium stearate, microcrystalline cellulose, and sodium starch glycolate; capsule shell: gelatin, printing ink, silicon dioxide, sodium lauryl sulphate, titanium dioxide, and yellow and red iron oxides.

40 mg
Each dark-orange capsule, marked "BMS 1967" and "40" contains 40 mg of stavudine. Nonmedicinal ingredients: lactose, magnesium stearate, microcrystalline cellulose, and sodium starch glycolate; capsule shell: gelatin, printing ink, silicon dioxide, sodium lauryl sulphate, titanium dioxide and yellow, and red iron oxides.

Do not take Zerit if you are allergic to stavudine or to any of the ingredients of the medication.

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

• didanosine
• Doxorubicin
• Hydroxyurea
• Orlistat
• ribavirin
• zidovudine

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 Zerit. 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 Zerit.

Fat redistribution: Zerit may change how fat is distributed on your body. With long-term use, fat may accumulate on the stomach, back, and breasts and be reduced on the arm, legs, and face. Notify your doctor if you start developing any changes in your body's appearance.

Immune system: When you start taking HIV medications such as stavudine, 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 HIV medications such as stavudine.

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

Lactic acidosis and enlarged liver: Zerit 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. Seek immediate medical attention if you notice any symptoms of this condition, such as:

• dizziness
• feeling cold
• irregular heartbeat
• lightheadedness
• nausea
• stomach pain
• tiredness
• vomiting
• weakness

Liver problems: Zerit can cause liver problems. Your doctor may monitor your liver function while you are taking Zerit, especially if you have risk factors for liver problems. Tell your doctor immediately about any signs of liver problems, such as:

• dark urine
• diarrhea
• loss of appetite
• nausea
• pale stools
• vomiting
• weight loss
• yellowing of the skin or whites of the eyes

Pancreatitis: Zerit may cause inflammation of the pancreas (pancreatitis). If you have previously had pancreatitis or are at risk for developing it, if you have gallstones, or if you regularly drink alcohol, you are at increased risk of developing pancreatitis when taking stavudine and should be closely monitored by your doctor while taking Zerit. Contact your doctor if you develop signs of pancreatitis, such as:

• back pain
• chills
• fever
• nausea
• rapid heartbeat
• swollen abdomen
• upper left abdominal pain

Peripheral Neuropathy: Stavudine may cause a rare but serious nerve disorder called peripheral neuropathy. This is more likely to occur in people who have had it previously, people who are taking medications that affect the nerves (e.g., didanosine), and people with advanced HIV disease, but it can occur at any disease stage. Tell your doctor immediately if you experience tingling, burning, numbness, or pain in the hands or feet.

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

Breast-feeding: It is not known whether stavudine passes into breast milk. Because HIV can be transmitted by breast milk, women who have HIV should not breast-feed.

Children: The safety and effectiveness of using Zerit have not been established for children less than 3 months old.