Why does knee pain get worse after applying a medicated plaster?

In general, increased knee pain after applying medicated plasters may be caused by drug irritation, allergic reactions, or inappropriate medication choice. The specific reasons are as follows:

1. Drug Irritation

Some pain-relieving plasters contain ingredients such as borneol or menthol, which may irritate the skin upon application, causing discomfort, pain, or a cooling sensation. This is considered normal and typically subsides after continued use for a period of time. No special treatment is required.

2. Allergic Reaction

If the patient has an allergic constitution and is sensitive to the plaster's components, the body may trigger an allergic response. Inflammatory mediators are released in the skin, leading to symptoms such as itching, stinging pain, redness, and warmth. In such cases, the plaster should be removed immediately. Under a doctor’s guidance, antihistamines such as chlorpheniramine maleate tablets, levocetirizine hydrochloride tablets, or loratadine tablets may be taken to manage the reaction.

3. Inappropriate Medication

If knee pain is caused by cold and dampness invading the joint, but a heat-clearing and dampness-removing plaster is used, it results in mismatched treatment. This can worsen the condition and lead to increased knee pain. Patients should seek treatment at a正规 medical institution and use medications under a physician’s diagnosis and guidance, avoiding self-medication without proper evaluation.

Besides the above common causes, increased pain could also result from conditions such as osteophyte formation (bone spurs), trauma, or fractures. During treatment, it is important to keep the joint warm. If symptoms do not improve with treatment, prompt consultation with an orthopedic specialist is necessary to avoid delayed diagnosis and more complicated management.