Cut by rusty metal! Do I need a tetanus shot?

Dear Alice,

If you step on a nail and have not had a tetanus shot in the last five years, how soon should a person be vaccinated? 24 hours? 48 hours?

Dear Reader, 

Although rusty metal has almost become synonymous with tetanus, stepping on a nail isn’t necessarily enough to send a person running, or hobbling, to get a tetanus shot. While tetanus is a serious bacterial disease, there are many factors to consider and symptoms to look for when determining whether or not a vaccine is needed. That being said, health professionals recommend that adults receive tetanus boosters at least every ten years, as preventing tetanus is much easier than curing it once infected. If you step on a nail and haven't had a tetanus booster in the last five years (or if you’re a little rusty on when your last booster was), visiting your health care provider to get it checked out is recommended. It’s best to seek treatment sooner rather than later (preferably within 48 hours) to increase your chances of treatment if, in fact, you're infected. Even if you’re still concerned, despite knowing the date of your last tetanus shot, having your medical provider take a look may provide some peace of mind.   

Interestingly, there seems to be a misconception about tetanus — it isn’t the rust that causes the infection, but rather it’s a type of bacteria known as Clostridium tetani that is on the nail. Spores of this bacterium are ubiquitous in the natural environment — lurking in soil, dust, as well as in animal intestines and feces. In fact, the rusty nail scenario isn't the only way this disease spreads. Any deep puncture can become infected with Clostridium tetani, as can burns, torn flesh, punctures from needles during drug use, animal bites and scratches, or other wounds contaminated with human and animal feces or saliva. 

Once these spores find a way into the body, they grow into bacterium that can produce a toxin known as tetanospasmin, which spreads systemically throughout the body. This toxin interferes with motor neurons, the neurons that control the muscles, and can produce muscle stiffness, rigidity, or spasms. For those who suspect they’ve been exposed to tetanus, there are a number of symptoms to watch out for: 

  • Spasms and stiffness of jaw (hence why tetanus is commonly known as “lockjaw”) 
  • Muscle spasms — often in the abdomen 
  • Painful muscle stiffness throughout the body 
  • Trouble swallowing 
  • Restlessness and irritability 
  • Fever 
  • Headache 
  • Sore throat 
  • Changes in blood pressure or heart rate 

In addition to these common symptoms, tetanus can also result in more serious complications, such as: 

  • Broken bones (due to involuntary spasms) 
  • Laryngospasm (involuntary tightening of vocal cords) 
  • Pneumonia 
  • Pulmonary embolism (a blood clot that has caused blockage in a main artery within the lungs) 
  • Cardiac arrest 
  • Difficulty breathing, and possibly leading to death 

Both lists adapted from the Centers for Disease Control and Prevention (CDC)

Symptoms may be localized, with muscle contractions in the part of the body where the infection began, or they may be generalized, affecting the whole body. Tetanus symptoms appear anywhere between 3 and 21 days after initial exposure. 

In order to diagnose tetanus, a health care provider will likely perform a physical exam, specifically looking for tell-tale signs such as muscle spasms, stiffness, and pain. Currently, there are no laboratory tests that diagnose tetanus. If a positive diagnosis is determined, the provider will give a treatment plan that may consist of either medication such as a tetanus antitoxin. This neutralizes any toxin that hasn't yet combined with nerve tissue, or antibiotics, which are used to fight tetanus bacteria in the body. With tetanus mortality rates as high as 25 percent in the United States and 50 percent worldwide, prevention via vaccination is especially critical — it's easy and close to 100 percent effective. In fact, almost all cases of tetanus have occurred in people who've never been immunized or who haven't had a tetanus booster shot within the preceding ten years. 

The tetanus vaccination works by causing an immune response in the body to an inactivated form of the tetanus toxin, thereby developing antibodies. In most cases, the vaccine is given to children as part of the diphtheria, tetanus, and pertussis (DTaP) shot. After the initial three shots that take place between the ages of two and six months, it’s recommended that children receive two booster shots, one between the ages of 15 and 16 months and the other between the ages of 11 and 18. In addition to the DTaP vaccine, there is also a tetanus, diphtheria and pertussis (Tdap) vaccine available for adolescents and adults who’ve never received the DTaP vaccine as an infant. After an individual receives the Tdap vaccine, it’s recommended that they also receive a tetanus booster every ten years. For folks traveling internationally, it's wise to make sure that their booster is up-to-date, as tetanus may be as tetanus may be more common and treatment may be less accessible overseas. 

So, Reader, if the wound is deep or if a person’s vaccination status is at all questionable, it may be worth a visit to a health care provider. For those who are certain their vaccinations are up to date and if the puncture is small, it may be safe to just clean the wound, treat it with antibiotic ointment, keep it covered and clean, and be on the lookout for any symptoms that could point to signs of a tetanus infection. As the saying goes, it's better to be safe than sorry; so, staying current with your tetanus vaccine is wise. You'll be more likely to avoid an infection if you happen to cut yourself on a sharp and dirty surface, and you'll avoid the mad dash to your health care provider's door. 

Last updated Oct 16, 2023
Originally published May 31, 1996

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