Common side effects of laxatives can vary depending on the type but often include cramping, bloating, gas, diarrhea, nausea, and increased thirst[3]. Lactulose, a commonly prescribed osmotic laxative, frequently causes diarrhea, especially when taken in high doses, and this occurs in more than 1 in 10 people[1]. Other common symptoms include stomach pain, bloating, and excess gas[3].
Serious side effects are rare but can include:
- Severe diarrhea or vomiting, which can lead to dehydration and electrolyte imbalance (abnormal sodium, potassium, or magnesium levels)[1][5].
- Muscle cramps, weakness, irregular heartbeat, confusion, dizziness, fainting, or seizures (often related to electrolyte disturbances)[1][5].
- Rectal bleeding, severe abdominal pain, or bloody stools[3].
- Severe allergic reactions (anaphylaxis) are very rare and can cause swelling of the face, lips, tongue, or throat, rash, difficulty breathing, paleness, confusion, or unresponsiveness[1].
Overuse or long-term use of laxatives can lead to dependency, worsened constipation, dehydration, and, in very rare cases, decreased colon function (for types other than bulk-forming laxatives)[3].
Contraindications: Do not take laxatives if you are allergic to the product, have certain rare sugar metabolism disorders (like galactosaemia for lactulose), undiagnosed rectal bleeding, heart problems, high blood pressure, or signs of gastrointestinal obstruction or perforation[2]. Always check with a doctor before combining laxatives with other medications, including over-the-counter or herbal supplements, due to possible interactions[4].
If you are pregnant, breastfeeding, have diabetes, or are on a restricted diet, consult a healthcare provider before using any laxative[4].