Difficulty swallowing after Botox: a warning sign, call for help

Swallowing the wrong way, feeling that food "won’t go down" or choking when drinking after a botulinum toxin injection is never trivial. Among the neck problems after an injection, this is the situation that calls for the greatest vigilance: it can interfere with breathing and lead to food or liquid entering the airways. It remains rare, but the rule is simple and has no exceptions: call emergency services (15 or 112 in France, or your local emergency number), even if the problem seems mild, then let the doctor who performed the injection know. The answers below help you understand what is happening; they do not replace an urgent medical examination.

Why can swallowing become difficult after an injection?

Swallowing uses many small muscles in the throat and neck, which contract in a precise order to move food towards the oesophagus rather than into the airways. Botulinum toxin works by blocking the signal between nerve and muscle. If it reaches these muscles, swallowing becomes less effective.

The labels describe two ways this can happen. The first is the toxin’s effect spreading away from the injection site: muscle weakness, swallowing and speech problems, difficulty breathing^1,2. The second is weakening of the muscles close to the injected area, when they take part in swallowing or breathing: this is the most common mechanism according to the US label of a type A toxin³. The neck is therefore the area most concerned, but difficulty swallowing has been reported after injections elsewhere.

Some people are more at risk. Injection is not recommended in people with a history of swallowing problems or aspiration (food or liquid entering the airways)^1,2,4. People with a disorder of the junction between nerve and muscle, such as myasthenia gravis, including when it has not yet been diagnosed, are at increased risk of severe dysphagia^2,3.

How soon after the injection does it appear?

Side effects of botulinum toxin usually appear in the first few days after the injection¹. But swallowing problems linked to spread of the toxin can occur later: the US label of a type A toxin states that they have been reported from hours to weeks after the injection³. Difficulty swallowing that appears several days after the session must therefore be taken as seriously as if it happened on the same day.

How long does it last?

The duration depends on how severe the effect is and on how long the injected toxin acts. In a review of published studies on the lower face and neck with a type A toxin, the only case of difficulty swallowing reported was mild and lasted about two weeks⁵. Conversely, the US label states that dysphagia can persist for several months and require tube feeding to maintain adequate nutrition and hydration³. To understand what the product’s duration of action depends on, see the page about how long botulinum toxin lasts.

Is it reversible?

Yes, the effect of the toxin on the muscles is temporary: it fades as the nerve endings become functional again². But difficulty swallowing can lead to complications during this period, in particular aspiration pneumonia, a lung infection caused by food or liquid entering the airways^1,2. The labels point out that difficulty breathing or swallowing is serious and can be fatal¹. This is why medical monitoring must not wait.

Is there a treatment?

There is no product that "cancels" the toxin once it has entered the nerve endings: at that stage, it can no longer be neutralised by antibodies⁶. Care consists of monitoring and protecting the person while waiting for the effect to wear off. If spread is suspected, the labels provide for medical monitoring over several days or even several weeks, hospital admission if needed and, when the breathing muscles are affected, breathing support until recovery^1,2. Adapting the diet and assessing swallowing are matters for the medical team.

What should you avoid?

• Do not wait for the problem to go away on its own, and do not just leave a message at the practice: call emergency services.
• Do not force down hard or dry food, and do not take big gulps quickly while waiting for help.
• Do not drive yourself to the emergency department if you have difficulty breathing.
• Do not accept another botulinum toxin injection before the effect of the previous one has gone: muscle weakness can be made worse by another toxin given before the effect of the first has worn off^2,3.

When should you see a doctor?

Immediately, by calling emergency services (15 or 112 in France, or your local emergency number), as soon as difficulty swallowing, a change in your voice, or difficulty speaking or breathing appears after an injection^1,2,4. Tell the emergency doctor the date of the injection, the areas treated and, if you know it, the product used; also mention any history of swallowing problems or neuromuscular disease. Once the situation is stable, let the doctor who performed the injection know.

If you only feel stiffness or tiredness in your neck, with no difficulty swallowing, speaking or breathing, the page on the stiff neck after an injection is more relevant. A problem in the lower face, with less mobile lips, is described on the page about the stiff chin; it should not be confused with true difficulty swallowing.