How much does Constulose cost?

Pricing for Constulose varies by insurance plan, dose, and pharmacy. Our database does not show a fixed cost because prices change faster than we can verify. For current pharmacy prices, check your insurance's formulary tier (in the prior-authorization section), use the GoodRx or Cost Plus Drugs deep links on this page, or ask your pharmacist to run a test claim. If a copay card is listed, it usually drops the out-of-pocket significantly for commercial insurance.

Does Constulose need prior authorization?

Constulose appears on 1 payer formulary in our database. PA requirements vary by payer — see the prior-authorization table on this page for specifics. In general, specialty and brand-name drugs are more likely to require PA than generic equivalents.

Is there a copay card or patient assistance program for Constulose?

We haven't verified an active copay card or PAP for Constulose in our current data. Check NeedyMeds or RxAssist for independent directories, or submit what you find via our "Report a broken link" form.

What is Constulose used to treat?

Constulose (generic: Lactulose) is indicated for Chronic Constipation, Constipation. Click any condition name on this page for more detail.

Does Constulose have a generic version?

The generic name for Constulose is Lactulose. Whether a generic is currently available depends on patent status — check the FDA Orange Book or ask your pharmacist. Generics are often substantially cheaper than brand-name drugs.

Constulose

Generic: Lactulose

Verified·Apr 23, 2026

Manufacturer: Actavis
NDC: 45963-439
RxCUI: 391937
Route: ORAL
ICD-10 indication: K59.00

Affordability Check

How much will you actually pay for Constulose?

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About Constulose

What is this medication? Constulose is a prescription oral solution that contains lactulose, which is a type of synthetic sugar used primarily to treat chronic constipation. It functions as an osmotic laxative by drawing water into the colon from surrounding body tissues, which softens the stool and makes it easier to pass. This mechanism helps to increase the frequency of bowel movements and provide relief for individuals struggling with irregular digestive patterns.

In addition to its use as a laxative, this medication is often prescribed to treat or prevent a condition called portal-systemic encephalopathy, a brain-related complication caused by severe liver disease. It works in the digestive tract to reduce the amount of ammonia that is absorbed into the blood. By lowering these ammonia levels, the medication helps to improve mental status and neurological clarity in patients whose livers are unable to filter toxins effectively.

Copay & patient assistance

Detailed copay and financial assistance information is not publicly available for this medication at this time. Please consult your pharmacist or the manufacturer's official patient support program for more details.

External links go directly to the manufacturer's portal. RxCopays does not receive compensation for referrals.

Compare pricing elsewhere

RxCopays doesn't sell drugs or take referral fees. Here are the transparent-pricing directories we recommend checking alongside your insurance formulary.

Cost Plus Drug Company

Mark Cuban's transparent-pricing pharmacy — manufacturer cost + 15% markup + $5 dispensing fee. No insurance needed. Search alphabetically for Lactulose.

Browse Cost Plus medications →

GoodRx

Compare local pharmacy prices with GoodRx coupons. Use the price with your insurance or without — whichever is cheaper.

Lookup Constulose →

NeedyMeds

Independent nonprofit directory of patient assistance programs, copay cards, and charity co-pay foundations.

Search for Lactulose →

RxAssist

PAP directory maintained by Volunteers in Health Care at Brown University. Free, no ads.

Search PAPs →

We deep-link because transparency helps patients. None of these partners pay RxCopays.

Prescribing information

From the FDA-approved label for Constulose. Official source: DailyMed (NLM) · Label effective Jun 1, 2022

Indications and usage

INDICATIONS AND USAGE For the treatment of constipation. In patients with a history of chronic constipation, lactulose solution therapy increases the number of bowel movements per day and the number of days on which bowel movements occur.

Dosage and administration

DOSAGE AND ADMINISTRATION The usual dose is 1 to 2 tablespoonfuls (15 to 30 mL, containing 10 g to 20 g of lactulose) daily. The dose may be increased to 60 mL daily if necessary. Twenty-four to 48 hours may be required to produce a normal bowel movement. Note: Some patients have found that lactulose solution may be more acceptable when mixed with fruit juice, water or milk.

Contraindications

CONTRAINDICATIONS Since lactulose solution contains galactose (less than 1.6 g/15 mL), it is contraindicated in patients who require a low galactose diet.

Warnings

WARNINGS A theoretical hazard may exist for patients being treated with lactulose solution who may be required to undergo electrocautery procedures during proctoscopy or colonoscopy. Accumulation of H 2 gas in significant concentration in the presence of an electrical spark may result in an explosive reaction. Although this complication has not been reported with lactulose, patients on lactulose therapy undergoing such procedures should have a thorough bowel cleansing with a non-fermentable solution. Insufflation of CO 2 as an additional safeguard may be pursued but is considered to be a redundant measure.

Drug interactions

Drug Interactions Results of preliminary studies in humans and rats suggest that non-absorbable antacids given concurrently with lactulose may inhibit the desired lactulose-induced drop in colonic pH. Therefore, a possible lack of desired effect of treatment should be taken into consideration before such drugs are given concomitantly with lactulose solution.

Adverse reactions

ADVERSE REACTIONS Precise frequency data are not available. Initial dosing may produce flatulence and intestinal cramps, which are usually transient. Excessive dosage can lead to diarrhea with potential complications such as loss of fluids, hypokalemia, and hypernatremia. Nausea and vomiting have been reported. To report SUSPECTED ADVERSE EVENTS, contact the FDA at 1-800-FDA-1088 or http://www.fda.gov/ for voluntary reporting of adverse reactions.

Use in pregnancy

Pregnancy Teratogenic Effects Pregnancy category B. Reproduction studies have been performed in mice, rats, and rabbits at doses up to 3 or 6 times the usual human oral dose and have revealed no evidence of impaired fertility or harm to the fetus due to lactulose. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Label text is reproduced as-is from the FDA-approved label. We do not paraphrase, summarize, or omit. Content above is for informational purposes only and is not medical advice. Always consult your prescribing clinician or pharmacist before making decisions about your medication.

Conditions we've indexed resources for

Click a condition to see copay cards, grants, and PA rules specific to it. For the full list of FDA-approved indications, see Prescribing information above.

Medicare Part D coverage

How Constulose appears across Medicare Part D plan formularies nationally. Source: CMS monthly Prescription Drug Plan file (2026-04-30).

Covered by plans

53%

2,899 of 5,509 plans

Most common tier

Tier 2

On 69% of covering formularies

Prior authorization required

of covering formularies

Tier	Formularies on this tier	Share
Tier 1 (preferred generic)	91	28%
Tier 2 (generic)	222	69%
Tier 3 (preferred brand)	9	3%
Tier 4 (non-preferred brand)	2	1%

Step therapy: 0% of formularies

Quantity limits: 0% of formularies

Coverage breadth: 324 of 65 formularies

How to read this:plans on the same formulary share tier + PA rules. Your specific plan's copay depends on (a) the tier above, (b) your plan's cost-share for that tier, (c) whether you're in the initial coverage phase or past the 2026 $2,000 out-of-pocket cap. For your exact plan, check its Summary of Benefits or log in to your Medicare.gov account. Copay cards don't apply to Medicare (federal law).

Prior authorization & coverage

Payer	PA	Step therapy	Copay tier
— Medicare Part D	—	—	—

Payer

Step therapy

Copay tier

—

Medicare Part D

—

Related drugs

How this page is sourced

Drug identity verified against openFDA NDC Directory.
Label text (when shown) originates from NLM DailyMed.
Copay and assistance URLs verified periodically; if you hit a broken link, tell us.