What Is DMSO?

Dimethyl sulfoxide, commonly known as DMSO, is a chemical compound that has been used as a bladder instillation treatment for interstitial cystitis (IC) since the 1970s. It remains the only intravesical (inside-the-bladder) treatment specifically approved by the US Food and Drug Administration for IC, which gives it a somewhat unique regulatory status among bladder instillation therapies 1.

The medical-grade formulation used for bladder treatment is called RIMSO-50, which contains a 50% solution of DMSO in water. This is quite different from the industrial-grade DMSO available in hardware shops or the lower-concentration products sold for muscle pain—those should never be used for bladder treatment.

I should be honest from the outset: DMSO has been around for decades and clearly helps some patients with IC and painful bladder syndrome, but it is not a miracle treatment. It works for some people and not for others, and even among responders, it manages symptoms rather than curing the underlying condition.

How Does DMSO Work?

Despite its long history of use, researchers still do not fully understand how DMSO produces its therapeutic effects. Several mechanisms have been proposed.

Anti-inflammatory Action

DMSO appears to reduce inflammation in the bladder wall. Laboratory studies show it can inhibit the release of inflammatory substances from mast cells, which are immune cells found in high numbers in the bladder tissue of many IC patients 2. Whether this translates directly into clinical benefit is harder to prove, but the theory fits with the symptom relief many patients report.

Muscle Relaxant Properties

DMSO seems to relax smooth muscle tissue, including the bladder wall. For patients experiencing bladder spasms or painful muscle contractions, this relaxant effect may contribute to symptom relief.

Analgesic Effects

DMSO has mild pain-relieving properties. It may block certain pain signals in nerve fibres, though this effect is less well characterised than its anti-inflammatory actions.

Tissue Penetration

One unusual property of DMSO is its ability to penetrate biological membranes readily. This allows it to carry other substances deeper into tissues, which is why some clinicians combine DMSO with other medications like heparin or steroids in so-called “cocktail” instillations. The DMSO acts as a carrier vehicle.

My take: The honest answer is that we do not have a complete picture of why DMSO works when it does work. The mechanisms are probably multiple and overlapping. What matters practically is whether it helps your symptoms, not whether we can explain precisely why.

What Does the Evidence Show?

DMSO has an unusual evidence profile. It was approved for IC treatment in 1978 based on relatively limited data by modern standards, and subsequent research has been somewhat sparse. Here is what we know.

The Original Approval Studies

The initial trials that led to FDA approval involved 213 patients who received DMSO instillations. About two-thirds reported symptomatic improvement 1. However, these were open-label studies without placebo controls, so some response may have been placebo effect.

Randomised Trials

A later randomised, double-blind, crossover study compared DMSO with saline placebo in 33 patients. The DMSO group showed statistically significant improvements in symptoms compared to placebo, with about 53% achieving objective improvement 3. This remains one of the better-designed studies we have.

Comparative Data

One study compared DMSO directly with sodium hyaluronate (another bladder instillation treatment) in patients with IC. Both treatments produced improvement, though interestingly, patients receiving hyaluronate reported slightly better outcomes. The difference was not statistically significant, but it does suggest that DMSO is not necessarily superior to newer alternatives 4.

Combination Therapies

Some clinicians use DMSO as part of a “bladder cocktail” containing multiple ingredients. A study examining a cocktail of DMSO, heparin, and hydrocortisone found that 64% of patients experienced at least 50% improvement in symptoms, with benefits lasting an average of 8 months 5.

Reality check: The evidence base for DMSO is smaller and older than you might expect for an FDA-approved treatment. Most studies are relatively small, and the methodology varies. That said, consistent reports of benefit across multiple studies over several decades suggest it genuinely helps a meaningful proportion of IC patients. Response rates across studies typically fall in the 50-70% range.

The Treatment Process

If your urologist recommends DMSO treatment, here is what the process typically involves.

Preparation

Before your first treatment, your doctor will likely confirm that you do not have an active urinary tract infection. DMSO should not be instilled into an infected bladder, as it could potentially worsen the infection or carry bacteria deeper into tissues.

You will be asked to empty your bladder before the procedure. Some clinicians recommend drinking fluids normally on treatment days, while others suggest limiting intake for a few hours beforehand to allow longer retention time.

The Instillation Procedure

The procedure itself is straightforward:

A thin catheter is inserted through your urethra into the bladder
Approximately 50ml of the DMSO solution is slowly instilled
The catheter is removed
You are asked to retain the solution for as long as comfortable, typically 15-30 minutes
You then urinate to empty the solution

The whole process takes about 20-30 minutes including the retention period. Most patients manage it without any anaesthesia, though some clinics offer lidocaine gel to numb the urethra before catheterisation.

Treatment Schedule

The standard protocol involves treatments every one to two weeks, typically for six to eight sessions. Many clinicians start with weekly treatments for the first month, then move to fortnightly intervals.

After completing the initial course, some patients maintain their improvement without further treatment. Others require periodic “maintenance” or “top-up” treatments, perhaps every few months, to sustain symptom control. Your urologist will work with you to find the right frequency.

If you are going to respond to DMSO, you will usually know within four to six treatments. If there is no improvement by that point, continuing treatment is unlikely to help, and your doctor will probably suggest trying an alternative approach.

Side Effects: The Garlic Problem

DMSO has a distinctive side effect profile that you should know about before starting treatment.

The Garlic-like Odour

This is the most famous DMSO side effect, and for many patients, it is the most bothersome. DMSO is metabolised in the body to dimethyl sulfide, which is excreted through the lungs. This produces a garlic or onion-like odour on the breath and sometimes through the skin.

The smell typically appears within a few hours of treatment and can persist for one to three days. Some patients find it mild and tolerable; others describe it as socially embarrassing. The odour does not reflect any danger to your health—it is simply an unavoidable consequence of how your body processes the chemical.

Practical tip: Some patients schedule treatments before weekends or days when they will not have much social contact. The smell is real, and people around you may notice it. Worth planning accordingly.

Temporary Symptom Flare

Some patients experience a temporary worsening of bladder symptoms in the first few hours or day after treatment. This might include:

Burning or stinging during urination
Increased urgency or frequency
Mild pelvic discomfort

These effects usually settle within 24-48 hours. If they persist or become severe, contact your healthcare team.

Other Possible Effects

Less commonly reported effects include:

Headache (usually mild and temporary)
Nausea
Diarrhoea
Skin irritation if DMSO contacts the skin during administration

Eye Lens Changes

This is a concern that requires explanation. Studies in animals showed that very high doses of DMSO over prolonged periods could cause changes to the lens of the eye. Because of this finding, some guidelines recommend periodic eye examinations for patients on long-term DMSO therapy.

However, the doses used in those animal studies were far higher than those used in human bladder treatment, and documented cases of lens problems in humans receiving standard DMSO bladder instillations are essentially non-existent 1. Many experts consider the eye examination requirement outdated and overly cautious, though practices vary. Discuss this with your urologist.

Who Should Not Use DMSO?

DMSO is contraindicated in several situations:

Active urinary tract infection. The infection should be treated and cleared before starting DMSO therapy.

Pregnancy. While the actual risk in humans is unknown, DMSO crosses the placenta and should be avoided during pregnancy.

Breastfeeding. Insufficient data on excretion in breast milk; generally avoided as a precaution.

Known hypersensitivity. If you have had a reaction to DMSO previously, do not use it again.

There are no absolute contraindications related to other medications, though DMSO could theoretically enhance the absorption of any other substances applied to the same area. Let your doctor know about all medications you are taking.

DMSO vs Other Bladder Instillations

If you are exploring treatment options for IC or PBS, you may wonder how DMSO compares with alternatives.

Versus Sodium Hyaluronate (Cystistat)

Sodium hyaluronate products work by replenishing the protective GAG layer on the bladder lining. They have a better side effect profile than DMSO—no garlic odour—and some studies suggest similar or better efficacy. However, they are not FDA-approved for IC specifically, which affects availability and insurance coverage in some healthcare systems.

Versus Alkalinised Lidocaine (Cystilieve)

Cystilieve and similar preparations work by directly anaesthetising the bladder, providing more immediate pain relief. They address symptoms differently than DMSO and are sometimes used in combination or rotation with other instillation therapies.

Versus Heparin

Intravesical heparin is another option targeting the GAG layer. It is often combined with DMSO in cocktail instillations. Some patients who do not respond to DMSO alone do better with combination therapy.

My honest view: There is no clear “best” bladder instillation for everyone. DMSO has the advantage of decades of use and FDA approval, plus some patients respond to it better than to newer alternatives. However, the garlic odour is a genuine quality-of-life issue. If you have a choice, discussing the pros and cons of each option with your urologist makes sense rather than defaulting to any particular treatment.

Combination or “Cocktail” Instillations

Some clinicians mix DMSO with other ingredients to create bladder cocktails. Common additions include:

Heparin: Another GAG-replenishment agent
Hydrocortisone or triamcinolone: Corticosteroids to reduce inflammation
Sodium bicarbonate: To alkalinise the solution and potentially reduce irritation
Lidocaine: For immediate pain relief during and after instillation

The evidence for these combinations is largely anecdotal and based on clinical experience rather than rigorous randomised trials. That said, many patients and clinicians report good results, and the approach is widely used.

The logic is that combining agents with different mechanisms might produce better results than any single agent alone. Whether this actually happens is hard to prove without proper comparative studies, but the approach is considered reasonable within the IC treatment community.

Questions to Ask Before Starting DMSO

If your urologist suggests DMSO treatment, consider asking:

How many DMSO treatments have you administered, and what results have your patients experienced?
What should I expect in terms of the garlic odour—how bad is it really?
If I do not respond after four to six treatments, what alternatives would you recommend?
Do you use DMSO alone or in combination with other agents?
How often will I need maintenance treatments if the initial course works?
Is periodic eye monitoring still required, and if so, why?

Making Your Decision

DMSO is not a first-line treatment for most patients with IC or PBS. Typically, you would try oral medications and dietary modifications before moving to bladder instillations. But when those approaches have not provided adequate relief, DMSO deserves serious consideration.

The treatment has genuine evidence supporting its use, even if that evidence is older and less robust than we might like. It helps somewhere between half and two-thirds of patients who try it. The main downside is the garlic odour, which some people find intolerable and others manage to live with.

If the odour is a dealbreaker for you, discuss alternatives like sodium hyaluronate with your urologist. If you can tolerate it, DMSO remains a reasonable choice—after all, there is a reason it has stayed in use for nearly 50 years.

References

Hanno PM. Painful bladder syndrome/interstitial cystitis and related disorders. In: Wein AJ, ed. Campbell-Walsh Urology. 9th ed. Saunders; 2007:330-370. PubMed
Badelino V, Bryan GT. DMSO: Review of its actions in interstitial cystitis. J Urol. 1987;137(2):390-393. PubMed
Perez-Marrero R, Emerson LE, Feltis JT. A controlled study of dimethyl sulfoxide in interstitial cystitis. J Urol. 1988;140(1):36-39. PubMed
Riedl CR, Engelhardt PF, Daha KL, Morakis N, Pflüger H. Hyaluronan treatment of interstitial cystitis/painful bladder syndrome. Int Urogynecol J. 2008;19(5):717-721. PubMed
Peeker R, Haghsheno MA, Holmäng S, Fall M. Intravesical bacillus Calmette-Guerin and dimethyl sulfoxide for treatment of classic and nonulcer interstitial cystitis. J Urol. 2000;164(6):1912-1915. PubMed