Anal safety: the flared base rule, and what else matters

This is the one area of the category where a design detail is a genuine medical matter rather than a preference. It is worth five minutes before any purchase.

Why the flared base rule exists

The rectum is not a closed cavity. It continues into the colon, and the muscles of the anal canal contract in a way that can draw an object further in rather than push it out. Once something passes beyond the reach of those muscles, it does not come back on its own.

Retrieval then means a hospital visit, and sometimes a surgical one. Emergency departments deal with this routinely — the staff are neither shocked nor judgemental — but it is an entirely avoidable situation.

A flared base is a base wider than the widest insertable part, wide enough that it cannot pass through. A ring, a broad flange or a T-bar all qualify. A tapered point, a small ball or a narrow neck ending in a rounded tip does not.

We treat the absence of a flared base as an automatic fail in these categories, whatever else the product does well.

Material matters more here, not less

Porous materials cannot be fully sanitised — fluid and bacteria sit in microscopic channels that washing does not clear. In a context involving gut flora, that is a more serious proposition than elsewhere.

Buy non-porous: silicone, glass or stainless steel. If you use something porous, use a condom with it and replace it rather than trusting a deep clean. The materials guide explains how to tell which you have.

Surface finish matters too. Run a fingernail along any moulding seam — a raised or rough seam is both a hygiene trap and a comfort problem.

Lubricant is not optional here

Unlike the vagina, the rectum does not self-lubricate. Lubricant is a requirement, and you will need noticeably more of it, reapplied more often, than you might expect.

Use water-based unless you have a specific reason not to. It is compatible with every material and every barrier method. Silicone lubricant lasts longer but can degrade silicone products; oil destroys latex condoms. Full detail in the compatibility guide.

Avoid anything marketed as “desensitising” or containing numbing agents. Discomfort is information — it is the signal telling you to stop or slow down. Removing that signal removes your ability to notice injury while it is still minor.

Size and progression

Start considerably smaller than you think necessary. Diameter matters far more than length, and the narrowest part of most products is not where the pressure is felt.

Progress across sessions, not within one. Tissue here is thinner and less elastic than vaginal tissue and tears more readily — and small tears are both painful and an infection route.

Sharp pain is a stop signal, not something to work through.

Cleaning

Wash with mild unscented soap and warm water before and after every use, paying attention to seams and the join where any base meets the shaft.

Solid 100% silicone, glass and steel items with no electronics can be boiled for a few minutes to sanitise properly. Never boil anything containing a motor or battery — it destroys the seal, and a damaged lithium cell is a fire risk. Full detail in the cleaning guide.

Do not use a product anally and then vaginally without washing thoroughly in between, or better, using a fresh condom. Transferring gut bacteria is a common and easily avoided cause of infection.

When to seek medical help

Go to an emergency department, without delay or embarrassment, if:

• Something has gone in and cannot be retrieved
• There is bleeding that does not stop quickly, or more than a trace
• There is severe or persistent pain
• There is fever, or abdominal pain and swelling, in the hours or days afterwards

Do not attempt retrieval with improvised tools — that reliably turns a straightforward procedure into a complicated one. Clinicians deal with this frequently and will simply get on with it.

This is general safety information, not medical advice. We are product testers, not clinicians. If you have a health concern, a pre-existing condition, or symptoms after use, speak to a doctor, pharmacist or sexual health clinic.