Penicillin for Sickle Cell Disease

Reviewed by: HU Medical Review Board | Last reviewed: February 2023

Children under 5 years old who have sickle cell disease (SCD) have a higher risk of severe infections. This is because SCD can damage the spleen. The spleen is an important part of the immune system needed to remove certain types of bacteria from the blood.

Children should be started on penicillin prophylaxis once the diagnosis is established or at least by 2 months of age. To prevent infections, children with SCD should take oral penicillin until they are 5 years old. Children over 5 years old should continue to take it if they have had their spleen removed or have had a previous severe pneumococcal infection.

Combined with vaccinations, penicillin has greatly improved survival rates of children with SCD. Continued education about the importance of penicillin can help parents and caregivers improve their child’s healthcare.

Why is penicillin an important treatment for sickle cell disease?

Children with SCD are vulnerable to certain types of bacterial infections. This is because blocked blood flow in the spleen prevents the spleen from working. The spleen is important to filter out certain types of bacteria from the blood, including Streptococcus pneumoniae (pneumococcus).1,2

Penicillins are a group of antibiotics that kill or block the growth of bacteria. Penicillins weaken the cell wall of these bacteria. This causes bacteria to eventually burst and die. The type of penicillin used in SCD is called “penicillin VK.” Penicillin VK is given by mouth and is most effective against infections caused by spleen disorders.1,3

Pneumococcus infections can quickly become severe in children with SCD. Because of this, preventing infections is usually more effective than treating them. Children with SCD should take penicillin from 2 months old to 5 years old. This is often called penicillin “prophylaxis” because it is taken to prevent an infection.1

How do we know that penicillin prevents infections in people with sickle cell disease?

Penicillin greatly reduces the risk of infections in people with SCD. The first evidence of this was published in 1986. In the study, children between 3 months and 3 years old took either penicillin or placebo (inactive medicine) twice a day. The study ended early because penicillin was so effective. Penicillin reduced the incidence of pneumococcus infection by 85 percent.4

The study also found that penicillin is more effective when it is started earlier. This is the main reason why every newborn is now screened for SCD. Early diagnosis allows doctors to start penicillin treatment before the age of 4 months.1,4

Until the 1990s, up to 30 percent of children with sickle cell anemia died from infections. Early diagnosis and penicillin treatment have reduced this to only 3 percent.4-6

What are the possible side effects and risks of penicillin?

People with SCD do not have any more risks associated with penicillin than people without SCD. Side effects and allergic reactions to penicillin are rare but can occur. Some side effects of penicillin VK include:1,3

  • Nausea
  • Vomiting
  • Abdominal pain
  • Diarrhea
  • Hives or rashes
  • Sore mouth and tongue

Get emergency help immediately if you notice symptoms of an allergic reaction, such as:3

  • Fever or chills
  • Puffiness or swelling around the face
  • Shortness of breath
  • Skin rash, hives, itching

These are not all the possible side effects of penicillin. Talk to your doctor about what to expect from taking penicillin. You also should call your doctor if your child has any changes that concern you when taking penicillin.

Children can use other antibiotics, such as erythromycin, if they are allergic to penicillin.1,7

Another concern is that pneumococcus bacteria will become resistant to penicillin over time. This happens when the bacteria develop ways to prevent penicillin from working. Some studies have shown that people with SCD who take penicillin are no more likely to have penicillin-resistant bacteria.1,8,9

However, it is still a concern that those with sickle cell may experience the emergence of resistant pneumococcal bacteria, so they should work closely with their doctor about the proper use of penicillin (compliance and evaluating if it is needed after age 5) and how to treat acute infections. Doctors may still use other types of antibiotics to treat an acute infection.1,8,9

Things to know about penicillin

Once children with SCD reach 5 years old, they are much less likely to experience a pneumococcus infection. This is because their immune systems have developed the ability to respond to pneumococcus. Studies have shown that penicillin does not significantly reduce the risk of infection after age 5.1,10

Many children stop taking penicillin after 5 years old. However, some continue taking it, especially if they have had their spleen removed or have had a severe pneumococcus infection before.1,11

Sticking to a penicillin prophylaxis plan is often difficult. Children with SCD have a higher risk of infection when they do not take penicillin. Infections can happen quickly even after 1 missed dose (10 to 20 hours without penicillin). Continued education to parents and caregivers about the importance of penicillin has helped improve rates of people sticking to the plan.1,12,13

Before your child begins treatment for SCD, tell their doctor about all other health conditions and any other drugs, vitamins, or supplements they take. This includes over-the-counter drugs.

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