Citanest Side Effects: What to Expect and When to Call Your Doctor

Citanest (prilocaine hydrochloride) is an amide-type local anesthetic administered by dentists during dental procedures. While it is generally well tolerated at normal dental doses, patients and providers should understand its side effect profile, its unique methemoglobinemia risk, and when symptoms warrant medical attention. Note that Citanest Plain has been discontinued in the US — this article covers the full safety profile for patients who may have received it in the past, or who might receive Citanest Forte if it is still available.

Common Side Effects of Citanest (Prilocaine)

Most side effects from dental local anesthetics — including prilocaine — are mild and temporary. Common effects include:

• Numbness and tingling: The expected effect of the anesthetic; soft tissue numbness lasts approximately 1.5 to 2.5 hours after a standard injection.
• Lip and cheek swelling: Mild swelling at the injection site is common and typically resolves within hours.
• Injection site soreness: Mild discomfort where the needle was inserted, usually resolving within 1-2 days.
• Paresthesia: Persistent numbness or tingling beyond the expected duration. Most resolves within weeks, but rare cases lasting more than one year have been reported. This can involve the lip, tongue, or oral tissues.
• Accidental biting: Because you cannot feel your lip or cheek while numb, biting injuries are possible. Do not eat while numb.

The Most Serious Risk: Methemoglobinemia

Prilocaine's unique serious risk — compared to other dental local anesthetics — is

methemoglobinemia. This is a condition where the iron in red blood cells is converted to a form that cannot carry oxygen effectively. It occurs because prilocaine is metabolized in the liver and kidneys to ortho-toluidine, a compound that converts hemoglobin to methemoglobin.

At normal dental doses (40-80 mg, or 1-2 cartridges), methemoglobinemia is extremely unlikely in healthy adults. It becomes a concern when the total dose exceeds 600 mg (8 cartridges) in adults. However, certain patients are at higher risk even at lower doses:

• Patients with G6PD deficiency
• Patients with congenital or idiopathic methemoglobinemia
• Patients with cardiac or pulmonary compromise
• Infants under 6 months of age
• Patients taking phenazopyridine, sulfonamides, dapsone, or nitrate medications

Symptoms of Methemoglobinemia to Watch For

Symptoms typically appear 2-4 hours after administration. They include:

• Bluish or grayish skin color (cyanosis), especially of the fingernails, lips, and mucous membranes
• Shortness of breath or difficulty breathing
• Fatigue and weakness
• Confusion or altered mental status
• Headache and dizziness

If you notice bluish skin or difficulty breathing after a dental procedure involving prilocaine, seek emergency medical care immediately. Methemoglobinemia is treated with intravenous methylene blue (1-2 mg/kg over 5 minutes) and responds quickly to treatment.

Systemic Toxicity Side Effects (Rare)

Systemic local anesthetic toxicity is rare at dental doses but can occur with accidental intravascular injection or overdose. Signs include:

• CNS: lightheadedness, ringing in the ears, metallic taste, slurred speech, numbness of the tongue, convulsions
• Cardiovascular: slow or irregular heartbeat, low blood pressure, cardiac arrest in severe cases

When to Call Your Dentist or Doctor

Contact your dentist or doctor if, after receiving Citanest:

• Numbness or tingling persists beyond 24 hours (possible persistent paresthesia)
• You develop bluish discoloration of the skin, lips, or fingernails (call 911 or go to the ER)
• You experience significant swelling, hives, or signs of allergic reaction
• You have unusual pain, infection signs, or difficulty opening your mouth days after the procedure

For more on drug interactions that increase side effect risk, see Citanest Drug Interactions: What to Avoid.

Learn more about Citanest's uses and dosage in our complete guide: What Is Citanest? Uses, Dosage, and What You Need to Know in 2026.