Vasalgel / RISUG
Polymer Vas-Occlusion - India's RISUG and the US Vasalgel / Plan A Program
Evidence grade 2 of 5, Thin. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Investigational; RISUG in late-stage trials in India, Vasalgel/Plan A in preclinical-to-early development. Not FDA-approved (2026)
Reference only. Not medical advice.
What can go wrong
Procedure-related risks resemble vasectomy (scrotal pain, swelling, hematoma, infection) plus uncertainties specific to an implanted polymer: local inflammation/fibrosis of the vas, incomplete or delayed reversal, and limited long-term human safety data. Human reversal has not been robustly demonstrated in published Western trials as of 2026.
This is something to take to a clinician. The Atlas can tell you what is known about vasalgel / risug in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
RISUG (Reversible Inhibition of Sperm Under Guidance) is an injectable polymer - styrene maleic anhydride dissolved in DMSO - placed into the vas deferens, where it coats the lumen and chemically disrupts sperm as they pass, rather than fully blocking flow. Developed in India by Sujoy Guha over decades, it has been studied in long-running Indian trials. Its Western counterpart, Vasalgel (a related hydrogel, advanced by the Parsemus Foundation and later as 'Plan A' by NEXT Life Sciences/Contraline-style efforts), aims for a reversible, long-acting, non-hormonal occlusion that can be flushed out with a second injection to restore fertility.
A reversible vasectomy: inject a gel into the vas, dissolve it later to restore flow.
What people take it for
These are the reasons people give for taking it. They are not effects it has been shown to have.
How it is supposed to work
Under local anesthesia the polymer gel is injected into the lumen of each vas deferens. RISUG's charged SMA polymer coats the vas wall and is thought to disrupt the membranes of passing sperm (a contact effect), while Vasalgel-type hydrogels act more as a porous physical filter/barrier. Crucially, the polymer is intended to be removable: a follow-up injection of a solvent dissolves or flushes the gel, restoring sperm passage - the mechanism that distinguishes these from permanent vasectomy.
Why decades of promise haven't produced a product
RISUG has shown durable contraceptive effect in Indian men in long-running studies, and animal work (including primates and dogs for Vasalgel) demonstrated reversal. But regulatory progress has been slow: questions about manufacturing standardization, reliability and timing of reversal in humans, long-term local effects on the vas, and - for the US programs - funding and sponsorship have repeatedly delayed approval. Reversal data in humans remain limited, and 'reversible vasectomy' marketing outruns the published evidence.
What it does to fertility
Designed as reversible contraception via vas occlusion. Reversal by solvent injection is demonstrated mainly in animals; reliable, well-characterized human reversal remains the key unproven claim.
What people get wrong
Often saidRISUG/Vasalgel is an approved reversible vasectomy you can get today
ActuallyBoth remain investigational; RISUG is in trials in India and Vasalgel/Plan A in early development - neither is FDA-approved or widely available in 2026.
Often saidReversal is proven
ActuallyReversal is well-shown in animals and is the central design goal, but robust human reversal data are limited; the 'reversible' claim is not yet fully validated in people.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
At a glance
- RISUG material
- Styrene maleic anhydride (SMA) copolymer in DMSO solvent
- RISUG originator
- Sujoy Guha, India (research spanning the 1980s onward)
- Western analog
- Vasalgel / 'Plan A' hydrogel (Parsemus Foundation; later NEXT Life Sciences)
- Reversal concept
- Second injection (e.g., DMSO/bicarbonate) to dissolve/flush the polymer
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Vasalgel / RISUG. A short entry is not a safe entry.
- Timeline. We have not built the dated record of research and regulatory events.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
- Where we land. We have not taken a position on this yet.
Sources
The studies below are named and described, but not linked. You cannot open them from here and check our reading against them, which means this page is our summary of the literature rather than a document you can verify. Weigh it accordingly until the links exist.
The studies that matter
Guha et al. - RISUG clinical studies (India)1990s-2000s
Intravasal SMA polymer produced prolonged azoospermia/contraceptive effect in men in Indian trials
Parsemus Foundation / Vasalgel preclinical (rabbit, primate)2016-2017
Vasalgel produced contraception in male rabbits and rhesus monkeys, with reversal demonstrated in some animal work