What are the side effects of penicillin?

Generally, penicillin is available in various dosage forms such as tablets and injections. Possible side effects of penicillin include seizures, nausea and vomiting, anemia, kidney function impairment, and pain. It is recommended to use the medication as directed by a physician. Detailed explanations are as follows:

1. Seizures

When high doses of penicillin are administered, its concentration in the body exceeds the normal metabolic and clearance capacity, leading to accumulation. The protective effect of the blood-brain barrier against high concentrations of penicillin weakens, allowing the drug to enter the central nervous system and directly act on nerve cells in the cerebral cortex, disrupting their normal electrophysiological activity and triggering seizures.

2. Nausea and Vomiting

After oral administration of penicillin antibiotics, the drug directly contacts the gastrointestinal mucosa. Its chemical properties stimulate receptors on the mucosal lining. These receptors transmit the stimulation signals to the gastrointestinal nerves, causing abnormal rhythm and intensity of gastrointestinal motility, thereby resulting in symptoms such as nausea and vomiting.

3. Anemia

Penicillin, as a hapten, may combine with proteins in the body to form complete antigens after entering the system. The immune system recognizes these antigens and produces antibodies targeting red blood cells. These antibodies bind to red blood cells, activating the complement system, which leads to red blood cell destruction. When the destruction exceeds the compensatory capacity of bone marrow hematopoiesis, anemia occurs.

4. Kidney Function Impairment

Penicillin is primarily excreted through the kidneys. When administered in high doses, the quantity of drug processed by the kidneys per unit time significantly increases, exceeding the normal excretory capacity. Additionally, in patients with pre-existing renal insufficiency, kidney excretory function is already compromised, making drug accumulation more likely. Drug accumulation exerts toxic effects on renal tubular epithelial cells, causing tubular damage and resulting in symptoms of kidney dysfunction such as proteinuria, hematuria, and oliguria.

5. Pain

When penicillin is administered via intramuscular injection, the drug is injected into muscle tissue. Differences in osmotic pressure and pH between the drug solution and the intramuscular environment create physical and chemical irritation to the local muscle tissue. This irritation triggers an inflammatory response in the local tissue, releasing inflammatory mediators that stimulate nerve endings, thus causing pain.

When using penicillin, it is essential to strictly follow the indications and dosage guidelines, and monitor the patient's response. If any adverse symptoms occur, discontinue the medication immediately and seek medical attention. Furthermore, penicillin is contraindicated in patients with known allergies to it, and a skin test should be conducted prior to administration to assess the presence of allergic reactions.