Botulinum toxin type A injections, best known under the brand name Botox, temporarily relax the muscles that create certain lines on the face. People ask three things: what is actually in the injection, how risky it is, and what to do afterward. This guide answers from the US prescribing label and from the NHS, and it separates what is documented from what practitioners simply tell their patients.

Key takeaways

  • A vial of Botox Cosmetic contains botulinum toxin type A, human albumin and sodium chloride; other brands have their own labels.
  • The FDA label says the effect on glabellar (frown) lines lasts about 3 to 4 months, and it carries a boxed warning about spread of the toxin.
  • Aftercare rules differ between practitioners and are not set out on the label I read, so ask for written instructions and ask who to call.

What is in a Botox injection?

I read the US Food and Drug Administration’s label for Botox Cosmetic (the copy I opened was revised 11/2019 and carries a note that it may not be the latest). It describes a sterile, vacuum-dried purified botulinum toxin type A, made from a bacterium, Clostridium botulinum, and supplied as a powder that is mixed with preservative-free saline before use. Each 50-unit vial contains the toxin complex, 0.25 mg of human albumin and 0.45 mg of sodium chloride. A 100-unit vial contains 0.5 mg of albumin and 0.9 mg of sodium chloride. There is no preservative.

Two details are worth knowing. The albumin is derived from human blood; the label states that it carries an “extremely remote risk” of transmitting viral disease, and that no transmission has been identified for licensed albumin. And units are not interchangeable: the label says Botox units cannot be compared to or converted into units of other botulinum toxin products. Other brands exist; the American Society of Plastic Surgeons names Botox, Dysport, Xeomin, Jeuveau and Daxxify. I did not read their labels, so do not assume the contents match.

How does it work, and how long does it last?

The toxin blocks the nerve signal to the muscle it is injected into, so the muscle relaxes (ASPS says it blocks “the nerve signals to the muscle”). On the label, Botox Cosmetic is approved for adults for the temporary improvement of moderate to severe frown lines between the eyebrows, lines at the outer corners of the eyes and forehead lines. The label says the injected muscles begin to weaken one to two days after injection, with the effect increasing over the first week, and that the effect on frown lines lasts about 3 to 4 months. Individual results vary, so ask what to expect for the area you want treated.

What are the risks?

The label begins with a boxed warning titled “distant spread of toxin effect.” It says effects can spread beyond the injection area, that symptoms have been reported from hours to weeks after injection, and that swallowing and breathing difficulties can be life threatening. The label places the greatest risk in children treated for spasticity, and also notes it can occur in adults with certain underlying conditions. It adds that it found no definitive serious reports of distant spread associated with cosmetic use at the labeled doses. It tells patients to seek immediate medical attention for breathing, speech or swallowing difficulty.

The most common reactions listed are:

  • Frown lines: drooping eyelid (3%)
  • Lines at the outer eye: eyelid swelling (1%)
  • Forehead lines: headache (9%) and drooping brow (2%)

Those are percentages from clinical trials, not guarantees. A single case report from 2025 described botulism after unlicensed toxin injected at home by a non-medical person; it is one case, but it shows why the source of the product matters.

What should you ask about aftercare?

Many websites list rules such as lying flat for hours, avoiding exercise or heat, or never touching the area. I did not find a list like that in the label I read, and practitioners give different instructions. Instead of trusting a generic list, ask:

  • What should I avoid, and for how long? Please write it down.
  • When will the effect appear, and when should I come back for a check?
  • What is normal bruising or swelling, and what should make me call you?
  • Which symptoms need urgent care, such as trouble swallowing or breathing?
  • Is there a charge for adjustments, and who handles problems if I have flown home?

Tell the prescriber about every medicine and supplement you take; what to avoid is their decision, not a generic list’s.

Who should inject it?

Rules differ by country, and I verified only the UK. There the NHS says botulinum toxin is a prescription-only medicine, prescribed after a consultation, and that you should know who the prescriber is, who will inject, what training and experience they have and what the insurance arrangements are. The page was last reviewed in June 2023. Wherever you are treated, ask for the practitioner’s registration, the product name and its packaging. Be wary of bargain offers and of practitioners who advertise only on social media, which the NHS lists among things to avoid. Our guide to the influencer trap covers how to check credentials.

If you are combining injections with a trip for surgery, ask your surgeon how they fit the timeline; see combining facial procedures, brow lifting with rhinoplasty and lip fillers.

Sources

All pages were opened and checked in October 2026.