Allopurinol Side Effects

by on January 18, 2012


The side effects of Allopurinol (Zyloprim) are generally mild and include drowsiness, nausea and headaches. Until you know how allopurinol will affect you, you should avoid operating a car or other heavy machinery. In rare cases, Allopurinol can cause a serious reaction known as Stevens-Johnson syndrome. If you experience a rash among your side effects, you should report this to a doctor immediately to avoid dangerous and potentially life-threatening complications.

Common Allopurinol Side Effects

Allopurinol side effects are uncommon. Even the most prevalent effects typically occur in about 1 percent of patients taking the medication. Side effects that have been reported include the following:

  • Nausea
  • Vomiting
  • Diarrhea
  • Drowsiness
  • Headaches
  • Fever
  • Heartburn
  • Nosebleeds
  • Hair loss
  • Muscle and joint pain
  • Change or loss of taste
  • Tingling or burning feelings in the feet or hands

If you experience any of the above side effects for a prolonged period of time or notice them worsening, you should contact your healthcare provider immediately. You should also talk to your doctor if these common side effects are affecting your daily activities.

Serious Allopurinol Side Effects

Some patients are allergic to allopurinol. If you experience any of the side effects listed below, you may be experiencing a severe allergic reaction. Contact your doctor immediately, even if your symptoms are mild. In an allergic reaction, symptoms can worsen very rapidly.

  • Rash or hives
  • Itching
  • Difficulty breathing
  • Tightness of the chest
  • Swelling of the face, mouth or throat

Many other side effects are equally serious, though not associated with an allergy to the drug. You should contact your healthcare provider immediately if you experience any of the following allopurinol side effects:

  • Pain with urination
  • Blood in the urine
  • Seizures
  • Yellowing of the whites of the eyes or skin
  • Infrequent urination
  • Unusual bruising or bleeding
  • Unexplained weakness
  • Flu-like symptoms including chills, body aches and fever
  • Tingling sensation
  • Numbness
  • Muscle weakness
  • Skin conditions including redness, blistering and peeling
  • Sore throat
  • Persistent or frequent infections
  • Itching
  • Loss of appetite
  • Weight loss
  • Eye irritation


Though seemingly innocent, a rash can be one of the most dangerous side effect you can experience while taking Allopurinol. If you notice any kind of rash, you should contact your doctor immediately, no matter how mild. This rash could be the first indication of Stevens-Johnson syndrome. This side effect, if left untreated, could lead to serious liver damage or death.

Allopurinol and your Kidneys

Side effects are more prevalent and severe in individuals with decreased kidney function. As kidney function declines with age, older patients will be more likely to struggle with allopurinol side effects than those who are younger. If you have kidney disease, your usage of this medication should be closely monitored. Drink at least 8 to 10 glasses of water each day to help prevent the formation of kidney stones while taking allopurinol medications.

Allopurinol and the Immune System

One of the side effects associated with Allopurinol that you may experience is a lowered immune system. Taking allopurinol can make you more prone to contracting infections and illnesses. Take extra precautions around those that are sick such as washing your hands frequently, never sharing food or drinks and even wearing a mask in the case of close exposure to sick individuals. Your doctor should perform regular blood tests to evaluate your blood cells while taking Zyloprim. It is very important that you keep these appointments so you can catch any dangerous side effects as early as possible.

Allopurinol (Zyloprim) is an effective treatment for gout and related diseases with few serious side effects. The best way to use this medication is to stay as mindful of gout attacks as possible. Taking allopurinol early on can effectively prevent an attack. However, taking allopurinol medications while an attack is occurring will not help and may even cause the gout to worsen. Talk to your doctor about other medications you can take along with Allopurinol to treat active gout attacks.