Best over-the-counter options for constipation

Pulls and holds water in the colon so stool softens and passes more easily; the MiraLAX Drug Facts label lists it for occasional constipation, 17 g once daily dissolved in 4–8 oz of liquid, generally producing a bowel movement in 1 to 3 days.

The best-supported OTC option. The 2023 AGA–ACG guideline for chronic idiopathic constipation gave PEG a STRONG recommendation (moderate certainty), citing more bowel movements, better stool form, and less straining vs placebo; it is well tolerated and inexpensive.

Caution: Label: do not use for more than 7 days without a doctor; children 16 and under should ask a doctor. Label also says do not use if you have kidney disease except under a doctor's supervision. Loose stools/diarrhea are the main side effect from too much; do not combine with starch-based swallowing thickeners. Stop and ask a doctor for rectal bleeding.

Adds soluble fiber that holds water in stool, making it bulkier and softer so the bowel can move it along; works in roughly 12–72 hours (NHS: up to 3 days), so it is not a fast option.

A sensible, gentle first choice — the class the NHS and pharmacists suggest trying first when buying without a prescription. The 2023 AGA–ACG guideline gives fiber (psyllium) a CONDITIONAL recommendation.

Caution: Must be taken with a full glass (at least 8 oz) of water; the label carries a genuine choking warning and says not to take it if you have difficulty swallowing. Can cause bloating and gas — start low. Take at least 2 hours apart from other medicines. Not the right tool if you are dehydrated or cannot drink enough fluids.

A saline/osmotic laxative that draws water into the bowel; the Milk of Magnesia label says it usually produces a bowel movement in ½ to 6 hours — faster than fiber or PEG.

Effective for short-term relief and useful when quicker action is wanted; magnesium oxide earned a CONDITIONAL recommendation in the 2023 AGA–ACG guideline. Not a daily-use product.

Caution: Label: ask a doctor before use if you have kidney disease or are on a magnesium-restricted diet — reduced kidney function can let magnesium build to dangerous levels. Can interact with prescription drugs. See a doctor for a bowel-habit change lasting over 14 days or if you need a laxative more than 1 week.

Stimulates intestinal wall muscles to contract and push stool along; both labels say they generally produce a bowel movement in 6 to 12 hours — the fast movers, useful as rescue or when a clinician expects constipation (e.g., starting opioids).

Effective but positioned for short-term/rescue use. The 2023 AGA–ACG guideline gave bisacodyl a STRONG recommendation specifically for SHORT-TERM use or rescue, and senna a CONDITIONAL recommendation. NIDDK: use stimulants only if constipation is severe or other treatments have not worked.

Caution: Do not use for longer than 1 week unless directed by a doctor; long-term reliance risks a colon less able to contract on its own. Bisacodyl: do not chew/crush, and do not take within 1 hour of an antacid or milk. Both: STOP and ask a doctor for rectal bleeding or failure to have a bowel movement — possible signs of a serious condition. Cramping is common.

A surfactant that lets more water and fat into stool so it is softer; the label lists relief of occasional constipation, working in 12 to 72 hours.

The gentlest and most-reached-for option, but the WEAKEST evidence: multiple reviews find it performs little better than placebo, and the 2023 AGA–ACG guideline did not recommend it. Best for keeping stool soft to avoid straining (post-surgery, hemorrhoids, anal fissure), NOT as a reliable treatment when you are already backed up — PEG or fiber is more likely to help.

Caution: Do not use with mineral oil unless a doctor directs. Same stop rules: see a doctor for rectal bleeding, no bowel movement, or need for use beyond 1 week.

Mineral oil coats stool and the bowel; enemas/suppositories act rectally. They can work but carry extra risks — mineral oil can interfere with nutrient absorption and is dangerous if aspirated.

Best treated as clinician-guided rather than casual first-line self-care. MedlinePlus specifically says not to start mineral oil without talking to your provider.

Caution: Avoid mineral oil in anyone with swallowing difficulty or aspiration risk, and in young children. Talk to a provider before starting; not a routine self-care choice.