Last update Jan. 20, 2026

Flavoxate Hydrochloride

Likely Compatibility

Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.

Anticholinergic smooth muscle relaxant with antimuscarinic action used to relieve spasticity, inflammation, pain, and incontinence of the urinary tract. Oral administration in 3 doses per day.

At the time of the last update, we found no published data on its excretion in breast milk.

Its pharmacokinetic data (moderately high molecular weight and distribution volume and high percentage of plasma protein binding) (Guay 2003, Bertoli 1976) make it unlikely to pass into breast milk in clinically significant amounts.

The antimuscarinic effect may reduce prolactin production (Masala 1982, De Martino 1980). Once lactation is established, milk production depends more on stimulation and regular emptying of the breast than on prolactin concentration.

Side effects are very rare and occasional use would pose a low risk during breastfeeding.

Monitor milk production and anticholinergic symptoms in the infant: irritability, nausea or constipation.

Until more data on this drug in relation to breastfeeding is published, alternatives with a known pharmacokinetic profile that is safer for breastfeeding (greater protein binding, shorter half-life and lower oral bioavailability) may be preferable, especially during the neonatal period and in cases of prematurity.

Alternatives

  • Oxybutynin (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)
  • Tolterodine Tartrate (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)

Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Flavoxate Hydrochloride in other languages or writings:

Group

Flavoxate Hydrochloride belongs to this group or family:

Tradenames

Main tradenames from several countries containing Flavoxate Hydrochloride in its composition:

Pharmacokinetics

Variable Value Unit
Oral Bioavail. 100 %
Molecular weight 428 daltons
Protein Binding 99.5 %
VD 0.2 l/Kg
pKa 7.3 -
Tmax 1 - 2 hours
3.5 - 10 hours

References

  1. Guay DR. Clinical pharmacokinetics of drugs used to treat urge incontinence. Clin Pharmacokinet. 2003 Abstract
  2. Masala A, Alagna S, Devilla L, Rovasio PP, Rassa S, Faedda R, Satta A. Muscarinic receptor blockade by pirenzepine: effect on prolactin secretion in man. J Endocrinol Invest. 1982 Jan-Feb;5(1):53-5. Abstract
  3. De Martino F, De Matteo A, L'Abbate V, Soricelli A, Fontana A, Petrenga E, Cesarone M. [Inhibitory effects of atropine on serum prolactin levels after TRH stimulation]. Boll Soc Ital Biol Sper. 1980 Abstract
  4. Bertoli M, Conti F, Conti M, Cova A, Setnikar I. Pharmacokinetics of Flavoxate in man. Pharmacol Res Commun. 1976 Abstract

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