Tavalisse (fostamatinib)
An approved treatment for Immune Thrombocytopenia.
The same compound appears under different names depending on the context. Here is how to identify Fostamatinib wherever you encounter it, plus the key facts at a glance.
- Generic name
- Fostamatinib
- Brand name
- Tavalisse
- Development code
- R935788
- Drug class
- Kinase inhibitor (SYK inhibitor)
- Manufacturer
- Rigel Pharmaceuticals
- How it's taken
- The starting dose is 100 mg by mouth twice a day, with or without food.
A twice-daily pill for adults with chronic immune thrombocytopenia (ITP) whose platelets did not respond well enough to an earlier treatment. Instead of making more platelets, it slows their destruction by blocking SYK, a signal immune cells use to break down platelets coated with antibodies. It was approved by the FDA on April 17, 2018.
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Where Fostamatinib fits
A later-line option that works on platelet destruction rather than production, so it can make sense after TPO receptor agonists. Blood pressure, diarrhea and liver tests shape whether people stay on it.
How Fostamatinib works
In ITP, antibodies coat platelets, and immune cells in the spleen grab the coated platelets through Fc receptors and destroy them. That grab-and-destroy step depends on an enzyme called spleen tyrosine kinase (SYK). Fostamatinib is turned into its active form, R406, in the body, and R406 blocks SYK signaling, so fewer platelets are destroyed and the count can rise. It works on the destruction side of ITP, while TPO receptor agonists such as Nplate and eltrombopag work on the production side.
Mechanism: Oral spleen tyrosine kinase (SYK) inhibitor; its active form, R406, blocks the signal immune cells use to destroy antibody-coated platelets
Side effects and safety
- High blood pressure. New or worse high blood pressure is common and can be severe; a hypertensive crisis occurred in 1% of patients. Blood pressure is checked every 2 weeks until the dose is stable, then monthly.
- Liver problems. ALT or AST rose above 3 times normal in 9% of patients, usually recovering within 2 to 6 weeks after a dose change. Liver tests are done monthly.
- Diarrhea. Occurred in 31% of patients and was severe in 1%. Diet changes, fluids or anti-diarrhea medicine help; severe cases lead to a dose pause or change.
- Low white blood cells. Neutropenia occurred in 6% and can raise infection risk; counts are checked monthly.
- Harm to an unborn baby. Pregnancy is checked before starting. Use effective birth control during treatment and for at least 1 month after the last dose.
- Complete blood counts monthly until platelets are stable at 50,000 or higher, then regularly
- Liver tests (ALT, AST, bilirubin) monthly
- Blood pressure every 2 weeks until the dose is stable, then monthly
Tavalisse has no boxed warning. The label warns about high blood pressure (a hypertensive crisis occurred in 1% of patients), liver test changes (ALT or AST above 3 times normal in 9%), diarrhea (31%, severe in 1%), low white blood cell counts (neutropenia in 6%) and harm to an unborn baby. Against placebo in the 2 main trials, the most common side effects were diarrhea (31% against 15%), high blood pressure (28% against 13%), nausea (19% against 8%), dizziness (11% against 8%), raised liver enzymes (ALT 11% against 0%), respiratory infections (11% against 6%) and rash (9% against 2%). Women who can become pregnant should use effective birth control during treatment and for at least 1 month after the last dose.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Fostamatinib
The starting dose is 100 mg by mouth twice a day, with or without food. If platelets have not reached 50,000 per microliter after 4 weeks, the dose goes up to 150 mg twice a day. Tavalisse is stopped after 12 weeks if platelets have not risen enough to avoid significant bleeding. Strong CYP3A4 inhibitors, such as some antifungals and antibiotics, raise drug levels, and strong CYP3A4 inducers are not recommended with it.
Availability and cost
Only available as the brand-name product.
Brand oral kinase inhibitor. The FDA approved an AB-rated generic (Annora Pharma) on June 17, 2026; its launch is unconfirmed.
Help paying for Tavalisse
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
Tavalisse Copay Assistance Program: eligible patients with commercial insurance pay as little as $0 per prescription dispense. Sign up at tavalissecopay.com. Must be a US or US territory resident; restrictions apply.
For: private insurance · source - Insurance and case manager help
Rigel OneCare's patient support team checks insurance coverage, determines eligibility for copay and financial assistance programs and helps with enrollment. Call 1-833-744-3562 or 650-449-8646, Monday to Friday, 8 AM to 8 PM ET.
For: private insurance, Medicare, Medicaid, TRICARE, no insurance, underinsured · source
Good to know: Tavalisse.com mentions financial assistance beyond the copay program without describing it; third-party listings describe a free drug supply and an income-based program, which are not listed here until confirmed on Rigel's own pages. The FDA approved an AB-rated generic from Annora Pharma on June 17, 2026; launch unconfirmed.
- From a charity · NORD RareCareImmune Thrombocytopenia Medical Assistance fundOpen
Pays for: Medical and medication costs.
The foundation says: “Accepting new applications and re-enrollments for current year” - From a charity · NORD RareCareImmune Thrombocytopenia Premium Copay Assistance fundOpen
Pays for: Insurance premiums and copays.
The foundation says: “Accepting new applications and re-enrollments for current year” - From a charity · The Assistance FundThrombocytopenia fundWaitlist
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
The foundation says: “WAITLIST — Accepting Waitlist Patients. TAF is currently accepting requests to join the enrollment waitlist for this program. Waitlists a…”
Clinical trial results
Two identical 24-week trials, FIT-1 (NCT02076399) and FIT-2 (NCT02076412), randomized 150 adults with persistent or chronic ITP, 2 to 1, to Tavalisse or placebo. Most had tried several treatments, including steroids (94%), immunoglobulins (53%) and TPO receptor agonists (48%), and the median platelet count at the start was 16,000. A stable platelet response, 50,000 or higher on at least 4 of 6 visits in weeks 14 to 24, occurred in 18% on Tavalisse against 0% on placebo in FIT-1, a statistically significant difference, and in 16% against 4% in FIT-2, which was not statistically significant.
Development history
Rigel Pharmaceuticals developed fostamatinib, and the FDA approved Tavalisse on April 17, 2018 as the first SYK inhibitor for chronic ITP. On June 17, 2026 the FDA approved an AB-rated generic fostamatinib from Annora Pharma; we could not confirm that it is on pharmacy shelves yet.
Explore Immune Thrombocytopenia trials
Other Immune Thrombocytopenia treatments
Steroids and IVIG are usually tried first. When they are not enough, options include the TPO receptor agonists Nplate (romiplostim), Promacta and generic eltrombopag, Alvaiz and Doptelet (avatrombopag), which raise platelet production; Tavalisse and Wayrilz (rilzabrutinib), which slow platelet destruction; and rituximab or spleen removal.
Fostamatinib in Trial Friend News and Guides
Common questions about Fostamatinib
▸What is Fostamatinib (Tavalisse)?
A twice-daily pill for adults with chronic immune thrombocytopenia (ITP) whose platelets did not respond well enough to an earlier treatment. Instead of making more platelets, it slows their destruction by blocking SYK, a signal immune cells use to break down platelets coated with antibodies. It was approved by the FDA on April 17, 2018.
▸How does Fostamatinib work?
In ITP, antibodies coat platelets, and immune cells in the spleen grab the coated platelets through Fc receptors and destroy them. That grab-and-destroy step depends on an enzyme called spleen tyrosine kinase (SYK). Fostamatinib is turned into its active form, R406, in the body, and R406 blocks SYK signaling, so fewer platelets are destroyed and the count can rise. It works on the destruction side of ITP, while TPO receptor agonists such as Nplate and eltrombopag work on the production side.
▸What are the side effects of Fostamatinib?
Tavalisse has no boxed warning. The label warns about high blood pressure (a hypertensive crisis occurred in 1% of patients), liver test changes (ALT or AST above 3 times normal in 9%), diarrhea (31%, severe in 1%), low white blood cell counts (neutropenia in 6%) and harm to an unborn baby. Against placebo in the 2 main trials, the most common side effects were diarrhea (31% against 15%), high blood pressure (28% against 13%), nausea (19% against 8%), dizziness (11% against 8%), raised liver enzymes (ALT 11% against 0%), respiratory infections (11% against 6%) and rash (9% against 2%). Women who can become pregnant should use effective birth control during treatment and for at least 1 month after the last dose.
▸How is Fostamatinib taken?
The starting dose is 100 mg by mouth twice a day, with or without food. If platelets have not reached 50,000 per microliter after 4 weeks, the dose goes up to 150 mg twice a day. Tavalisse is stopped after 12 weeks if platelets have not risen enough to avoid significant bleeding. Strong CYP3A4 inhibitors, such as some antifungals and antibiotics, raise drug levels, and strong CYP3A4 inducers are not recommended with it.
▸Is Fostamatinib FDA approved?
Yes, Fostamatinib (Tavalisse) is FDA approved (2018) for the treatment of Immune Thrombocytopenia.
▸How is Tavalisse different from Promacta or Nplate?
Tavalisse slows the destruction of platelets, while Promacta, Nplate, Alvaiz and Doptelet push the bone marrow to make more of them.
How: it blocks SYK, a signal immune cells in the spleen use to break down antibody-coated platelets.
When used: for adults with chronic ITP after an earlier treatment did not work well enough.
▸How long does Tavalisse take to work?
The label says to stop it after 12 weeks if platelets have not risen enough.
Dose step-up: from 100 mg to 150 mg twice a day after 4 weeks if platelets are still under 50,000.
▸Is there a generic Tavalisse?
The FDA approved an AB-rated generic fostamatinib from Annora Pharma on June 17, 2026.
Availability: we could not confirm it is in pharmacies yet, so ask your pharmacist.
Source: Drugs@FDA, ANDA 217329
▸What are the side effects of Tavalisse?
The most common were diarrhea, high blood pressure, nausea, dizziness, raised liver enzymes, respiratory infections and rash.
Checks: blood pressure every 2 weeks until stable, and liver tests and blood counts monthly.
Pregnancy: use effective birth control during treatment and for at least 1 month after.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. National Library of Medicine, DailyMed · 2025-11. TAVALISSE (fostamatinib disodium hexahydrate) tablets: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=21149cc3-049b-43e2-b141-c9499160556c
- U.S. Food and Drug Administration. Tavalisse approval history. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=209299
- U.S. Food and Drug Administration. Fostamatinib tablets (Annora Pharma) approval. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=217329
- Rigel Pharmaceuticals. Rigel OneCare and Tavalisse copay assistance. https://www.tavalisse.com/support
- ClinicalTrials.gov. A Efficacy and Safety Study of R935788 in the Treatment of Persistent/Chronic Immune Thrombocytopenic Purpura (ITP) (FIT). https://clinicaltrials.gov/study/NCT02076399
- ClinicalTrials.gov. A Efficacy and Safety Study of Fostamatinib in the Treatment of Persistent/Chronic Immune Thrombocytopenic Purpura (ITP) (FIT). https://clinicaltrials.gov/study/NCT02076412