Tamiflu Side Effects

by on June 26, 2012


Tamiflu side effects are very rare. A small number of patients who take this medication may have more intense flu-like symptoms when they first begin the treatment, including nausea, vomiting, and headaches. These side effects will generally improve quickly. Individuals who take Tamiflu (oseltamivir) have a very low risk of developing more serious side effects, such as hepatitis or potentially fatal skin conditions, but this is extremely rare.

Common Tamiflu Side Effects

Only a small percentage of people who take Tamiflu will experience any side effects. The most frequently reported side effects are very similar to symptoms associated with influenza but only last for a short time. These symptoms may affect individuals who already have the flu, as well as those who are taking Tamiflu to prevent an influenza infection.

  • Nausea
  • Abdominal pain
  • Vomiting
  • Diarrhea
  • Headache

If the symptoms above persist or become worse, contact your doctor. In most cases, Tamiflu will reduce the duration of flu symptoms by at least one day and may prevent other flu related illnesses such as pneumonia.

Serious Tamiflu Side Effects

Most individuals will not experience any serious or severe side effects while taking Tamiflu. An allergic reaction to oseltamivir is possible and could be fatal if not treated promptly. Contact your doctor immediately if you have:

  • A skin rash
  • Hives
  • Blisters on the skin
  • Swelling, especially of the tongue or face
  • Unexplained hoarseness
  • Trouble swallowing
  • Difficult breathing
  • Itching

In very rare cases, individuals who take Tamiflu may suffer from other side effects. Discuss the risks below with your doctor before deciding if this medication is right for you.

  • Seizures
  • Elevated liver enzymes
  • Hepatitis
  • Severe confusion
  • Diabetes complications
  • Cardiac arrhythmia
  • Changes in mental state, particularly in children

If you experience any unusual symptoms while taking Tamiflu, either mental or physical, be sure to let your doctor know.


Oseltamivir can be used to treat and prevent the flu in children as young as one year old. In most cases, the medication is safe and effective. However, studies have found that the use of Tamiflu may increase the chance of abnormal behaviors, hallucinations, and possible self-endangerment, particularly in children between the ages of 10 and 19. Discuss the risks and benefits of Tamiflu with your child’s doctor before using the drug and closely monitor his or her behavior during treatment.


The side effects of Tamiflu during pregnancy are unknown. In some cases, this risk may be less dangerous to the mother and unborn baby than the effects of a serious flu infection. Your doctor can help you decide if you should take oseltamivir if you are pregnant or think you may be. If you are taking Tamiflu and learn that you are pregnant, let your doctor know immediately.

Tamiflu may pass through breast milk and is not recommended for children under the age of one. Do not take Tamiflu if you are breastfeeding.

Existing Conditions

Individuals who suffer from certain conditions are at a higher risk of experiencing serious Tamiflu side effects. Tell your doctor if you have any disease that lowers the efficiency of your body’s immune system, or if you have been diagnosed with a kidney, heart, or lung condition. The liquid suspension version of Tamiflu contains sorbitol and is not recommended for individuals with a fructose intolerance. Diabetes patients should talk to their doctor before taking Tamiflu because it may aggravate their symptoms.

Other Medications

There are other drugs besides FluMist that may have adverse interactions with oseltamivir. It is always a good idea to discuss all of the other medications, supplements, or herbal products you are taking with your doctor, but the drugs below could have more serious side effects when taken with Tamiflu:

  • Chemotherapy medications such as Rheumatrex, Rapamune, etc.
  • Medications that affect the immune system like azathioprine and cyclosporine
  • Prograf
  • Oral steroids including dexamethasone, prednisone, etc.

If you are currently taking any of these medications, you may still be able to safely take Tamiflu, but the dosage may need to be adjusted to ensure an effective treatment with minimal side effects.

More than 50 million people have taken Tamiflu to treat or prevent influenza since 1999 and only a small number of serious side effects have been reported. While Tamiflu side effects are rare, some people may feel the risk is not worth the minimal benefits that the medication can provide. This is particularly true in young patients who may be at a higher risk of developing abnormal thoughts or behaviors.