Doctors probably don't mention it because it is not yet a known, approved ITP treatment.
I'm not so sure that it's less harmful than other treatments after reading the side effects. Some of these are pretty serious:
The most common side effects were nausea and vomiting.
The most common side effects reported with this drug during studies for the treatment of influenza were nausea, vomiting, headache, bronchitis, insomnia, and vertigo. Nausea and vomiting were generally mild to moderate in severity and usually occurred on the first 2 days of therapy. Less than 1% of patients discontinued this drug early due to nausea and vomiting.
Side effects in prophylaxis studies were similar to those in treatment studies, most commonly nausea, vomiting, headache, and pain. Side effects that occurred more frequently than in treatment studies were aches and pains, rhinorrhea, dyspepsia, and upper respiratory tract infections.
Very common (10% or more): Headache (up to 18%)
Common (1% to 10%): Dizziness, vertigo
Frequency not reported: Drowsiness
Postmarketing reports: Seizure/convulsion.
Side effects with similar or higher incidence among placebo patients included dizziness and vertigo.
Very common (10% or more): Nausea
Common (1% to 10%): Nausea (without vomiting), vomiting, diarrhea, abdominal pain, upper abdominal pain, dyspepsia
Frequency not reported: Pseudomembranous colitis
Postmarketing reports: Gastrointestinal bleeding, hemorrhagic colitis.
Side effects with similar or higher incidence among placebo patients included diarrhea, abdominal pain, upper abdominal pain, and dyspepsia.
Common (1% to 10%): Nasal congestion, cough, sore throat, bronchitis, nasopharyngitis, upper respiratory tract infections, influenza, rhinorrhea, sinusitis
Frequency not reported: Pneumonia, peritonsillar abscess, congestion, rhinitis, dry sore throat, epistaxis, asthma, aggravated asthma.
Side effects with similar or higher incidence among placebo patients included cough, nasal congestion, sore throat, rhinorrhea, bronchitis, sinusitis, nasopharyngitis, upper respiratory tract infections, and influenza.
Common (1% to 10%): Insomnia
Frequency not reported: Mania
Postmarketing reports: Abnormal behavior, delirium, altered level of consciousness, confusion, delusions, hallucinations, agitation, anxiety, nightmares, self-injury.
Influenza can be associated with various neurologic and behavioral symptoms (including hallucinations, delirium, abnormal behavior), with fatal outcomes in some cases; such events may occur with encephalitis or encephalopathy but can occur without obvious severe disease. There are postmarketing reports (mostly in Japan) of delirium and abnormal behavior leading to injury, with fatal outcomes in some cases in influenza patients using this drug. Although frequency is unknown, based on usage, these events appear uncommon. These events were primarily reported in pediatric patients, often with abrupt onset and rapid resolution. The contribution of this drug to such events has not been established.
Side effects with similar or higher incidence among placebo patients included insomnia.
Side effects with similar or higher incidence among placebo patients included fatigue, pyrexia, influenza-like illness, and pain in limb.
Common (1% to 10%): Fatigue, pain, pyrexia, influenza-like illness, pain in limb, otitis media, earache
Uncommon (0.1% to 1%): Tympanic membrane disorder
Frequency not reported: Humerus fracture, malaise, sepsis, facial edema, ear disorder, accidental injury
Postmarketing reports: Hypothermia.
Side effects with similar or higher incidence among placebo patients included herpes simplex.
Common (1% to 10%): Herpes simplex
Uncommon (0.1% to 1%): Dermatitis (including allergic and atopic dermatitis)
Rare (less than 0.1%): Angioneurotic edema
Postmarketing reports: Rash, urticaria, eczema, serious skin reactions, toxic epidermal necrolysis, Stevens-Johnson syndrome, erythema multiforme.
Common (1% to 10%): Back pain, arthralgia, myalgia.
Side effects with similar or higher incidence among placebo patients included back pain, arthralgia, and myalgia.
Side effects with similar or higher incidence among placebo patients included dysmenorrhea.
Common (1% to 10%): Dysmenorrhea
Common (1% to 10%): Conjunctivitis (including red eyes, eye discharge, eye pain)
Rare (less than 0.1%): Visual disturbances.
Uncommon (0.1% to 1%): Elevated liver enzymes
Rare (less than 0.1%): Hepatic failure, fulminant hepatitis (including fatalities)
Frequency not reported: Hepatic function disorder, jaundice
Postmarketing reports: Hepatitis, abnormal liver function tests.
Postmarketing reports: Hypersensitivity reactions (e.g., allergic skin reactions), allergy, anaphylactic/anaphylactoid reactions, swelling of the face or tongue.
Frequency not reported: Unstable angina, sudden cardiopulmonary arrest
Postmarketing reports: Cardiac arrhythmia.
Frequency not reported: Hyperglycemia
Postmarketing reports: Aggravation of diabetes.
Frequency not reported: Anemia, pancytopenia, lymphadenopathy
Postmarketing reports: Thrombocytopenia