Side Effects

Drug information provided by: Micromedex

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common

  1. Anxiety
  2. black, tarry stools
  3. blood in the urine or stools
  4. body aches or pain
  5. burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  6. chest pain
  7. confusion
  8. congestion
  9. cough or hoarseness
  10. crying
  11. delusions
  12. dementia
  13. depersonalization
  14. depression
  15. diarrhea
  16. difficult or labored breathing
  17. dryness or soreness of the throat
  18. dysphoria
  19. euphoria
  20. feeling unusually cold
  21. fever or chills
  22. general feeling of discomfort or illness
  23. headache
  24. increased sweating
  25. joint pain
  26. loss of appetite
  27. lower back or side pain
  28. mental depression
  29. muscle aches and pains
  30. nausea
  31. nervousness
  32. painful or difficult urination
  33. paranoia
  34. pinpoint red spots on the skin
  35. quick to react or overreact emotionally
  36. rapidly changing moods
  37. redness at the place of injection
  38. runny nose
  39. shivering
  40. shortness of breath
  41. sore throat
  42. sweating
  43. tender, swollen glands in the neck
  44. tightness in the chest
  45. trouble with sleeping
  46. trouble with swallowing
  47. trouble with thinking or concentrating
  48. unusual bleeding or bruising
  49. unusual tiredness or weakness
  50. voice changes
  51. wheezing

Less common

  1. Irregular heartbeat


  1. Blurred vision or loss of vision
  2. skin rash, hives, or itching

Incidence not known

  1. Abdominal or stomach pain
  2. bleeding gums
  3. bloody or black, tarry stools
  4. change in walking and balance
  5. clay-colored stools
  6. clumsiness or unsteadiness
  7. confusion
  8. constipation
  9. coughing up blood
  10. dark-colored urine
  11. decreased urination
  12. difficulty with breathing or swallowing
  13. dizziness
  14. dry mouth
  15. fainting
  16. fast heartbeat
  17. full or bloated feeling
  18. increase in heart rate
  19. increased menstrual flow or vaginal bleeding
  20. lightheadedness
  21. loss of consciousness
  22. muscle cramps or spasms
  23. nosebleeds
  24. paralysis
  25. pressure in the stomach
  26. prolonged bleeding from cuts
  27. rapid, shallow breathing
  28. red or black, tarry stools
  29. red or dark brown urine
  30. seizures
  31. severe stomach pain
  32. shakiness and unsteady walk
  33. shakiness in the legs, arms, hands, or feet
  34. sunken eyes
  35. swelling of the abdominal or stomach area
  36. thirst
  37. trembling or shaking of the hands or feet
  38. unpleasant breath odor
  39. unsteadiness, trembling, or other problems with muscle control or coordination
  40. vomiting of blood or material that looks like coffee grounds
  41. wrinkled skin
  42. yellow eyes or skin

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  1. Acid or sour stomach
  2. aching muscles
  3. back pain
  4. belching
  5. decreased appetite
  6. difficulty with moving
  7. feeling of warmth
  8. general feeling of discomfort or illness
  9. hair loss
  10. heartburn or indigestion
  11. lack or loss of strength
  12. loss of memory
  13. muscle pain or stiffness
  14. pain in the back or joints
  15. pain in the limbs, muscles, or neck
  16. pain or tenderness around the eyes and cheekbones
  17. problems with memory
  18. redness of the face, neck, arms, and occasionally, upper chest
  19. sleeplessness
  20. stomach discomfort, upset, or pain
  21. stuffy nose
  22. sudden sweating
  23. swollen joints
  24. thinning of the hair
  25. unable to sleep
  26. weight loss

Incidence not known

  1. Being forgetful
  2. bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
  3. blistering, peeling, or loosening of the skin
  4. bone pain
  5. burning feeling in the chest or stomach
  6. change in vision
  7. difficulty with moving
  8. difficulty with speaking
  9. false beliefs that cannot be changed by facts
  10. hearing loss
  11. pain, swelling, or redness in the joints
  12. red, irritated eyes
  13. red skin lesions, often with a purple center
  14. seeing, hearing, or feeling things that are not there
  15. sores, ulcers, or white spots in the mouth or on the lips

Interferon alfacon-1 may cause a temporary loss of some hair. After treatment has ended, normal hair growth should return.

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.