Doctors of Reddit, what's something you've had to tell a patient that you thought for sure was common knowledge?

Have had to inform a few male patients that the condom only goes on the shaft and should not be pulled down to include covering of the testicles.

How a shorter slash fatter 5-millimeter oral syringe held more volume than a skinnier and longer 1-millimeter oral syringe.

How does this hold more liquid when it's shorter?

Also, I've seen almost every incorrect way to use an inhaler, upside down being fairly common.

People taking birth control pills only on the days they have intimacy.

I no longer assume anything as common knowledge.

I'd rather have someone be offended that I explain something basic than to have something

awful happen because I assume the patient knew something.

After putting a few stitches in a middle-aged guy's scalp, the family asked if he was okay.

The attending joked that his brain was still inside.

The family were stunned by this news.

I, the medical student, spent the next half hour informing the family that the brain

was inside the school and that a person couldn't live without one. They thought that the brain was

just to turn a phrase to reflect a person's common sense rather than an actual organ, sort of the

same as what they thought about the heart. I'm not a doctor, but I'm an ER nurse. I had a patient

come in for an STD check. She was very upset and

continued to tell me that she only had one partner. Progressing through my assessment, she further

divulged that even if he was sleeping with other people, it shouldn't matter because he uses a condom

every time and he makes sure to wash it thoroughly after every use. I asked what she meant when

she said he washes it after every use. She explained that he washed the condom with hot water and soap before he used said condom again.

I had to explain to her that condoms are a one-time use product.

...