Skin Home > Precautions and Warnings With OnabotulinumtoxinA

People who are allergic to any components of the drug should not take onabotulinumtoxinA. In addition to causing allergic reactions, this medicine has been known to cause vision changes, dry eyes, and other problems, so it's important to review the safety information with your healthcare provider before starting treatment with onabotulinumtoxinA. Precautions and warnings also apply to people who have heart disease, myasthenia gravis, or difficulty swallowing.

What Should I Tell My Healthcare Provider?

Prior to using onabotulinumtoxinA (Botox®), talk to your healthcare provider if you have:
Also, let your healthcare provider know if you are:
  • Pregnant or thinking of becoming pregnant
  • Breastfeeding.
You should also be sure to tell your healthcare provider about all of the medicines you take, including prescription and nonprescription medications, vitamins, and herbal supplements.

Specific OnabotulinumtoxinA Warnings and Precautions

Warnings and precautions to be aware of prior to using this medication include the following:
  • In rare cases, onabotulinumtoxinA can spread from the site of injection to distant parts of the body, potentially causing serious problems. This is more likely to occur if the drug is used to treat spasticity in children.
  • The medication can cause allergic reactions. If you notice an unexplained rash, itching, wheezing, swelling, or difficulty breathing, tell your healthcare provider right away.
  • OnabotulinumtoxinA can cause difficulty swallowing, which may cause serious problems. This is more likely if you already have swallowing problems or if you have a neuromuscular disease.


  • This medication can cause bronchitis and breathing problems. This can be dangerous for people who already have breathing problems.


  • In rare cases, there have been instances of heart problems occurring after a dose of onabotulinumtoxinA, particularly in people who already have heart disease. It is not clear if these problems were related to the drug. However, you should let your healthcare provider know if you have heart disease before receiving this medication.
  • OnabotulinumtoxinA contains albumin, a human protein. Theoretically, viruses or infectious proteins may be transmitted through albumin. However, no cases have been reported.


  • Some people treated with onabotulinumtoxinA for urine leakage due to an overactive bladder will have problems completely emptying their bladder. In some cases, this may require catheterization to empty the bladder and may be an ongoing problem. 


  • Sometimes, the medication can decrease your blinking reflex, especially if it is used near the eyes. This can dry out your eyes, increasing your risk of corneal abrasion or other eye problems. If your eyes seem to be dry, let your healthcare provider know right away.
  • Sometimes, onabotulinumtoxinA injections in the area near the eyes can cause vision changes. These changes are usually temporary.
  • OnabotulinumtoxinA can interact with a few different medications (see Drug Interactions With OnabotulinumtoxinA).
  • OnabotulinumtoxinA is considered a pregnancy Category C medication. This means that it may not be safe for use during pregnancy, although the full risks are not known (see Botox and Pregnancy).
  • It is not known if onabotulinumtoxinA passes through breast milk. Therefore, if you are breastfeeding or plan to start, discuss this with your healthcare provider prior to taking the drug (see Botox and Breastfeeding).
Written by/reviewed by:
Last reviewed by: Kristi Monson, PharmD;
Last updated/reviewed:
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