SIDE EFFECTS: See also Warning section. Headache or diarrhea may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. As your immune system gets stronger, it can begin to fight off infections you already had, possibly causing disease symptoms to come back. You could also have symptoms if your immune system becomes overactive. This reaction may happen at any time (soon after starting HIV treatment or many months later). Get medical help right away if you have any serious symptoms, including: unexplained weight loss, severe tiredness, muscle aches/weakness that doesn't go away, headaches that are severe or don't go away, joint pain, numbness/tingling of the hands/feet/arms/legs, vision changes, signs of infection (such as fever, chills, swollen lymph nodes, trouble breathing, cough, non-healing skin sores), signs of an overactive thyroid (such as irritability, nervousness, heat intolerance, fast/pounding/irregular heartbeat, bulging eyes, unusual growth in the neck/thyroid known as a goiter), signs of a certain nerve problem known as Guillain-Barre syndrome (such as trouble breathing/swallowing/moving your eyes, drooping face, paralysis, trouble speaking). This medication can cause severe nerve problems in the hands/feet/legs (peripheral neuropathy). Symptoms may include numbness/tingling/pain in the palms of the hand or soles of the feet. If you experience any of these symptoms, contact your doctor right away so that you can be monitored closely. Your doctor may decide to reduce or stop your dose of didanosine. Tell your doctor right away if you have any serious side effects, including: vision problems (such as blurred vision, difficulty seeing colors), vomiting up blood, belly/abdominal swelling, easy bruising or bleeding. Loss of body fat (such as in the face, arms, and legs) may occur while you are taking this medication. This effect may be permanent. Tell your doctor right away if you notice any changes in body fat. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking didanosine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: pancreatitis, kidney problems, liver problems (such as hepatitis, cirrhosis), nerve problems (such as peripheral neuropathy), alcohol use, high fat levels in the blood (triglycerides), gall bladder problems (such as gall stones), gout. Avoid alcoholic beverages because they may increase your risk for liver problems and pancreatitis. Didanosine may increase your risk of a heart attack. Discuss the risks and benefits of treatment with your doctor and ways to lower your risk of heart disease. Tell your doctor if you have heart problems, if you smoke, or if you have other conditions that increase your risk of heart disease such as high blood pressure, diabetes, or high cholesterol levels. Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products). Older adults may be at greater risk for pancreatitis while using this drug. During pregnancy, this medication should be used only when clearly needed. Treatment can lower the risk of passing HIV infection to your baby, and didanosine may be part of that treatment. Discuss the risks and benefits with your doctor. It is not known if this medication passes into breast milk. Because breast milk can transmit HIV, do not breast-feed.

DRUG INTERACTIONS: See also Warning section. Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products that may interact with this drug include: allopurinol, hydroxyurea, methadone, orlistat, drugs that are known to cause nerve problems (such as isoniazid, vincristine), drugs known to cause pancreatitis (such as pentamidine, ganciclovir, co-trimoxazole), ribavirin, stavudine.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.