How many piercings is typical?

Approximately 10% of adults in England (Bone et al., BMJ 2008, n=10,503) and 14% of US adults aged 18 to 50 (Laumann and Derick, JAAD 2006) have had a body piercing somewhere other than the earlobe. Among women aged 16 to 24 in England the figure is 46.2%, close to a coin toss. Earlobes don't count in any of these numbers, so someone with pierced ears and nothing else counts as unpierced by the survey's definition.

Women aged 16 to 24, at 46.2% with a non-earlobe piercing in the English data, and nobody else comes close. The rate falls to 18.7% for women aged 25 to 34 and 2.8% for those aged 45 to 54, while men aged 16 to 24 sit at 13.1%. Bone's team asked whether people had ever had a piercing, healed-over ones included, so the drop reflects who took it up rather than who took the jewellery out.

Many do, and a good share of people who get pierced eventually remove the jewellery, navel and tongue piercings especially. How fast the hole closes depends on the site and the gauge. A new piercing can close in hours to days, a well-healed one over weeks to months, and cartilage piercings in the ear or nose often never close fully, leaving a small permanent mark.

One to four in a session, depending on placement and your pain threshold, is what most experienced piercers will do. Each new piercing sets off its own local inflammatory response, and too many at once slow healing for all of them. High-trauma placements such as the navel, cartilage or genitals are normally done one at a time, while lobes are low-impact and can sensibly be done in pairs.

As many as your ear can heal, which in practice means three to five on the lobe for most people and a slower build on the cartilage. Piercers generally advise spacing new ear piercings at least four to six weeks apart so each one heals before the next goes in beside it. Cartilage placements (helix, tragus, daith, conch) heal over three to twelve months each, so the ceiling is set by healing time rather than by space.

There's no clean answer, because neither of these surveys has been repeated. The English figures come from fieldwork in early 2005 and the US ones from a telephone survey published in 2006. In 2005 the age gradient was steep, with 46.2% of women aged 16 to 24 pierced against 2.8% at 45 to 54, and those young women are now in their late thirties and forties, a shift the old figures can't see.

Swelling, going by the BMJ 2008 study (Bone et al., N=10,503), which recorded it with 15.4% of piercings held by 16 to 24 year olds, ahead of infection at 9.7%. Some complication of any kind followed 31% of their piercings. The wider literature adds perichondritis from ear cartilage piercings and cracked teeth from tongue and lip piercings. Hospital admission followed 0.9% of piercings in the BMJ study, so serious harm is rare and still real.

From 6 to 8 weeks for an earlobe with good aftercare up to a year for the slowest sites. Ear cartilage (helix, tragus, daith) takes 6 to 12 months and throws up irritation bumps along the way, the navel takes 6 to 12 months and can migrate if placed badly, and a nostril usually heals in 4 to 6 months. The tongue heals fastest on the surface at 4 to 6 weeks but needs care to protect the teeth. Surface piercings and dermal anchors are the hardest, healing over 3 to 12 months with higher rejection rates.

Implant-grade titanium (ASTM F136), implant-grade steel (ASTM F138), niobium, solid 14k to 18k gold and glass, which are the materials the Association of Professional Piercers (APP) recommends for a fresh piercing. Nickel is the most common cause of allergic contact dermatitis from piercing jewellery and turns up in many cheap alloys, and acrylic and unnamed-alloy pieces sold cheaply online cause trouble for healing piercings again and again. Safe metal costs more, which is one reason cheap piercings in unregulated settings carry higher complication rates whatever the piercer's technique.

In some industries, yes. A 2014 study by McElroy, Summers and Moore in Organizational Behavior and Human Decision Processes found that raters, both students and working adults, judged applicants with visible facial piercings less suitable for the job than the same applicants without them. Creative and technology employers, and media companies, are far more relaxed about it. What a piercing costs you at work depends on the industry, the role and where on your face or body it sits.

Highest in the first few weeks, before a tunnel of skin has formed around the jewellery, and the BMJ 2008 study recorded infection with 9.7% of piercings held by 16 to 24 year olds, while professional help was sought for 15.2% of them. Risk goes up with a piercing gun rather than a needle (guns can't be fully sterilised), with careless aftercare (unwashed hands, or alcohol and hydrogen peroxide, which damage the tissue), with a metal allergy, and with sites that carry a lot of bacteria such as oral and genital piercings. A regulated studio, proper jewellery and saline-only aftercare cut the risk a long way.