Anaspaz is a brand name for hyoscyamine sulfate, a prescription medication that reduces muscle spasms in the digestive tract, bladder, and kidneys. It belongs to a class of drugs called anticholinergics/antispasmodics, which work by slowing involuntary muscle contractions and decreasing the production of stomach acid and other bodily fluids. Anaspaz comes as a 0.125 mg orally disintegrating tablet.
How Anaspaz Works
Your digestive tract, bladder, and other organs contain smooth muscle that contracts automatically. In conditions like irritable bowel syndrome or bladder spasms, those contractions can become overactive, causing cramping, urgency, and pain. Hyoscyamine blocks a chemical messenger called acetylcholine from reaching these muscles, which calms the contractions and reduces fluid secretion. This is why the drug also works as a “drying agent” for excessive salivation, runny nose, and sweating.
The orally disintegrating tablet dissolves on the tongue and starts working within about 5 to 20 minutes, which is faster than a standard swallowed tablet (20 to 30 minutes). The effects last up to four hours per dose.
Conditions It Treats
Anaspaz is used for a broad range of conditions involving muscle spasms or excess secretions:
- Digestive disorders: irritable bowel syndrome, spastic colon, diverticulitis, peptic ulcer, acute enterocolitis, and abdominal cramps from visceral spasm
- Bladder and urinary problems: spastic bladder, cystitis, and neurogenic bladder
- Pain relief: biliary and renal colic, typically alongside other pain medications
- Other uses: reducing rigidity and tremors in Parkinson’s disease, controlling excess saliva, drying a runny nose, and managing excessive sweating
One important note: MedlinePlus and DailyMed both flag that several hyoscyamine products, including those sold under the Anaspaz name, have not been formally evaluated by the FDA for safety, effectiveness, and quality. This doesn’t mean the drug is dangerous, but it does mean it was marketed under older regulatory rules and hasn’t gone through the modern FDA approval process. Your prescriber is aware of this distinction when choosing it for you.
Dosage and How to Take It
For adults and children 12 and older, the typical dose is one or two tablets every four hours as needed, with a maximum of 12 tablets in 24 hours. Children ages 2 to 11 generally take half to one tablet every four hours, up to 6 tablets daily. It has not been studied in children under 2.
The disintegrating tablet can be placed on the tongue and allowed to dissolve, or it can be swallowed whole or taken sublingually (under the tongue). Some manufacturers recommend taking it 30 to 60 minutes before meals for the best effect. If you take antacids, separate them from your hyoscyamine dose by at least one hour before or two hours after, since antacids can reduce the drug’s effectiveness.
Common Side Effects
Because Anaspaz blocks acetylcholine throughout the body, not just in the target organ, its side effects tend to mirror that widespread suppression. Dry mouth is the most common complaint. You may also notice blurred vision, difficulty urinating, constipation, drowsiness, or dizziness. These effects are generally mild and dose-related, meaning they tend to ease if the dose is lowered.
Reduced sweating is a less obvious but clinically significant side effect. Because your body relies on sweating to cool itself, taking hyoscyamine in hot weather or during vigorous exercise increases your risk of heat stroke. Staying hydrated and avoiding prolonged heat exposure helps manage this risk.
More serious reactions, like a rapid heartbeat, confusion, or difficulty breathing, are uncommon but warrant prompt medical attention.
Brand Name vs. Generic Availability
Anaspaz was one of many brand names for hyoscyamine sulfate. Others include Levsin, Levbid, NuLev, and Ed Spaz, with at least 26 brand names marketed over the years. Today, the medication is widely available in generic form. If your pharmacy substitutes a generic version, the active ingredient and strength are the same. Extended-release formulations (like Levbid) last up to 12 hours per dose but work differently from the fast-dissolving Anaspaz tablet, so they aren’t interchangeable without your prescriber’s guidance.