See also Warning section.
Headache or diarrhea may occur. If any of these effects last or get worse, notify your doctor or pharmacist promptly.
Remember that this medication has been prescribed because your doctor 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 unsteadiness, loss of coordination, trouble swallowing/speaking/chewing, trouble moving your eyes).
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 MedWatch: The FDA Safety Information and Adverse Event Reporting Program.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.