Medical shock is a life-threatening drop in blood flow that can follow heavy bleeding, severe burns, allergic reactions or serious illness. American Red Cross, MedlinePlus and NIH guidance on the warning signs, how to position and keep the person warm, why to skip food and drink, and when to start CPR.

Most fainting spells are brief and harmless, but some signal a heart problem or a serious injury. American Red Cross, American Heart Association and NIH guidance on warning signs, what to do when someone faints, recovery, and the red flags that mean you should call 911.

An asthma attack can turn serious in minutes. Guidance from the CDC, the American Red Cross, the American Lung Association and NHLBI on early and emergency warning signs, how to help someone use a quick-relief inhaler, when to call 911 and how to keep asthma supplies ready in an apartment.

Naloxone can reverse an opioid overdose and is now sold over the counter. CDC, SAMHSA and FDA guidance on overdose warning signs, giving nasal naloxone, rescue breathing, the recovery position, Good Samaritan laws and where to keep naloxone at home.

Low blood sugar can turn dangerous in minutes for people with diabetes. American Diabetes Association, CDC and NIDDK guidance on hypoglycemia symptoms, the 15-15 rule, glucagon for severe lows, when to call 911 and how to plan for lows during outages and emergencies.

Electrical injuries can be hidden and deadly, and rescuers are often hurt trying to help. Mayo Clinic, American Red Cross and Electrical Safety Foundation International guidance on shutting off power, first aid after a shock, when to call 911 and why to stay at least 35 feet from downed lines.

Kitchen knives, broken glass and sidewalk falls cause most household cuts and scrapes. Mayo Clinic, American Academy of Dermatology and CDC guidance on stopping bleeding, cleaning a wound, bandaging, tetanus shots, when to get stitches and infection warning signs.

Bumps to the head are common after falls, especially in dark stairwells or on icy sidewalks. CDC HEADS UP, Mayo Clinic and Red Cross guidance on concussion symptoms, the danger signs that need 911, first aid for scalp bleeding, extra caution for older adults and people on blood thinners, and recovery basics.

Falls on icy sidewalks, stairwells and cluttered floors cause many sprains and fractures. Red Cross, Mayo Clinic and orthopedic guidance on telling a sprain from a strain or a break, the RICE method, how to make a simple splint, open fractures, when to call 911 and what to keep in your apartment first aid kit.

Most seizures end on their own within a few minutes, and the right first aid is simple. Epilepsy Foundation, CDC and Red Cross guidance on what to do during a seizure, when to call 911, the recovery position, myths to avoid, seizure action plans and how to prepare for seizures during emergencies and outages.