Tell your doctor if any of these unlikely but serious side effects occur

• Mental/mood changes
• Shaking
• Weakness

Tell your doctor if any of these rare but very serious side effects occur

• Fast/slow/irregular heartbeat

A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include

• Rash
• Itching/swelling
• Severe dizziness
• Trouble breathing

Other things to note

• Dizziness, headache, nausea, nervousness, or trouble sleeping may occur. If any of these effects persist or worsen, contact your doctor or pharmacist promptly.
• If your doctor has prescribed this drug, remember that your doctor has prescribed it because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

• Read directions carefully before start of therapy
• Drink plenty of water to help loosen mucus
• May make you dizzy. Use caution when driving.
• Review all drugs you are taking with your doctor
• For expectorant products : Unless MD directs, do not use in kids less than 6. Before using tell Dr. if you have phenylketonuria. Measure dose using a dosing spoon/cup/syringe. Reduce or avoid drinking alcohol.
• For suspension, oral products : Shake well & measure with dosing spoon/cup/syringe.
• For tablet products : Do not take more drug than directed. Call doctor if you are not getting better.
• For tablet, extended release products : Unless MD directs, do not use in kids less than 12. Swallow whole. Do not break/chew/crush/dissolve. Avoid other medicines containing the same drug.

• This drug may impair the ability to operate a vehicle, vessel (e.g., boat), or machinery. Use care until you become familiar with its effects.
• May cause dizziness
• Medication should be taken with plenty of water.
• For suspension, oral products : Shake well before using.
• For tablet, extended release products : Consult your doctor or pharmacist before breastfeeding.
• For tablet, extended release products : Do not chew or crush before swallowing.

Before taking this medication, tell your doctor if you've had:

• Breathing problems (e.g., asthma, emphysema)
• Diabetes
• A certain eye problem (glaucoma)
• Heart problems
• High blood pressure
• Kidney problems
• Overactive thyroid (hyperthyroidism)
• Trouble urinating (e.g., due to enlarged prostate)

Products that may interact with this drug include:

• Beta blockers (e.g., metoprolol, atenolol)
• Guanethidine
• Certain inhaled anesthetics (e.g., halothane)
• Methyldopa
• Tricyclic antidepressants (e.g., amitriptyline, desipramine)