What Is RIMSO-50? Uses, Dosage, and What You Need to Know in 2026

If you or someone you care for has been diagnosed with interstitial cystitis (IC) and a doctor has mentioned RIMSO-50, you may be wondering: what exactly is this medication, how does it work, and what should I expect? This article gives you the full picture.

What Is RIMSO-50?

RIMSO-50 is the brand name for a sterile 50% dimethyl sulfoxide (DMSO) aqueous solution. It has been FDA-approved since 1978 for the symptomatic relief of interstitial cystitis — and it holds the distinction of being the only FDA-approved bladder instillation therapy specifically indicated for this condition.

Dimethyl sulfoxide itself is an organosulfur compound with the chemical formula C2H6OS. It is a clear, colorless liquid with a distinctive odor when metabolized. In pharmaceutical form, it is highly purified, sterile, and specifically prepared for human intravesical use — unlike industrial or veterinary DMSO products, which should never be used in patients.

What Is Interstitial Cystitis?

Interstitial cystitis (IC), also called bladder pain syndrome (BPS), is a chronic condition characterized by bladder pain, pelvic pressure, and urinary urgency and frequency. It affects an estimated 3–8 million women and 1–4 million men in the United States. IC is not a bacterial infection — antibiotics do not treat it, and it requires specialized urology management.

The hallmark of IC is the absence of a clear infectious cause combined with persistent bladder pain. There is no cure, but treatments like RIMSO-50 can significantly reduce symptoms and improve quality of life.

What Is RIMSO-50 Used For?

RIMSO-50 is FDA-approved for one indication: the symptomatic relief of interstitial cystitis. It is not approved for:

Bacterial bladder infections (UTIs) — RIMSO-50 has no antibacterial activity

Arthritis or joint pain

Muscle sprains, skin burns, or wounds

Note: DMSO is available in industrial and veterinary forms that have been promoted for various off-label uses. These non-pharmaceutical forms are NOT safe for human bladder instillation and should never be used as substitutes for pharmaceutical-grade RIMSO-50.

How Is RIMSO-50 Given?

RIMSO-50 is an intravesical medication — it is placed directly into the bladder rather than swallowed or injected. The procedure works as follows:

A healthcare provider inserts a thin catheter into the bladder through the urethra. Lidocaine jelly is typically applied first to the urethra to minimize discomfort.

50 mL of RIMSO-50 solution is instilled into the bladder through the catheter.

The patient retains the solution in the bladder for 15 minutes.

The solution is expelled by normal urination.

The entire office visit for the instillation is typically brief. Patients can drive themselves home and resume normal activities in most cases.

RIMSO-50 Dosage Schedule

The standard RIMSO-50 dosing schedule is:

Induction phase: 50 mL instilled every 2 weeks until maximum symptomatic relief is achieved. Most patients receive 6–8 weekly or biweekly treatments during the initial course.

Maintenance phase: Once symptoms are controlled, the interval between instillations is gradually increased (monthly, then every few months, as tolerated).

Severe IC: Initial treatments may be done under anesthesia for patients with very sensitive bladders.

Is RIMSO-50 a Controlled Substance?

No. RIMSO-50 (dimethyl sulfoxide) is not a controlled substance and is not scheduled by the DEA. It is a prescription medication that requires a written or electronic prescription from a licensed provider, but there are no special prescribing restrictions or refill limitations based on DEA scheduling.

Who Should Not Use RIMSO-50?

Urinary tract malignancy: RIMSO-50 is contraindicated in patients with known or suspected bladder or kidney cancer.

Pregnancy: The safety of RIMSO-50 during pregnancy has not been established. Use only if the potential benefit clearly justifies the potential risk.

Active urinary infection: RIMSO-50 should not be administered if a urinary tract infection is present.

Finding RIMSO-50 When You Need It

Because RIMSO-50 is a specialty drug, it is not always readily available at all pharmacies. If your clinic is having trouble sourcing it, medfinder can help find pharmacies near you that have it in stock. medfinder contacts pharmacies on your behalf and texts you the results.

To learn more about the science behind how RIMSO-50 works, see: How Does RIMSO-50 Work? Mechanism of Action Explained in Plain English.