Yes. Medicines used for depression, anxiety, bipolar disorder, psychosis, ADHD and other mental health conditions can cause physical, emotional, sexual, sleep-related or behavioural side effects. The symptoms depend on the medicine, dose, other medicines or supplements being taken, and the individual person.
A symptom appearing after you start a medicine does not automatically mean the medicine caused it. Mental health conditions themselves, another illness, alcohol or recreational drugs, supplements, missed doses and medicine interactions can produce similar symptoms. The safest approach is to look at the timing and pattern of your symptoms and discuss concerns with a doctor or pharmacist.
Our Mental Health Medication Side Effects hub provides further guidance on medicines commonly used for mental health conditions.
How mental Health Medication Side Effect Symptoms can be linked to medicines or supplements
Side effects can appear when a medicine is first started, after the dose is changed, when another medicine or supplement is added, or sometimes after treatment has been used for longer.
Some side effects are relatively mild and may improve as the body adjusts. Others can persist or require a change to the treatment plan. A small number of reactions can be serious and need prompt medical assessment.
Mental health medicine side effect symptoms can include changes in sleep, appetite, weight, digestion, sexual function, energy, concentration and mood. Some people experience dizziness, headaches, nausea, sweating, tremor, restlessness or unusual sleepiness.
For example, antidepressants can be associated with symptoms including nausea, headaches, dizziness, sleep changes, agitation, sweating, sexual problems and changes in appetite or weight. The NHS notes that antidepressant side effects vary considerably between medicines and between people.
Antipsychotic medicines may cause a different pattern. Possible effects include sleepiness, dizziness, restlessness, tremor, changes in movement and weight or metabolic changes. Some people taking certain antipsychotics require monitoring of weight, blood glucose or blood lipids.
Timing clues
Think about when the symptom appeared in relation to your treatment. Useful questions include whether it started soon after a new prescription, followed a dose change, appeared after another medicine or supplement was added, or became worse after a missed dose.
Timing can provide useful information, but it cannot prove that a medicine caused the symptom. A doctor or pharmacist may need to consider your medical history, the known effects of the medicine, possible interactions and other explanations.
Medicines and product categories that may be associated with this symptom
There is no single set of mental health medication side effect symptoms. Different medicine groups affect the body in different ways.
Antidepressants include selective serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline reuptake inhibitors (SNRIs), older tricyclic antidepressants and other medicines. Possible side effects vary by medicine but may include digestive symptoms, headache, sleep problems, drowsiness, sexual difficulties, sweating, agitation and changes in weight or appetite.
Anti-anxiety medicines can include antidepressants as well as benzodiazepines and other treatments. Some anti-anxiety medicines can affect alertness or coordination, while longer-term use of benzodiazepines can lead to tolerance or dependence. They should not be stopped or reduced suddenly without appropriate professional guidance.
Antipsychotic medicines may cause sleepiness, restlessness, tremor, movement-related symptoms or metabolic changes. Long-term treatment with some antipsychotics can also be associated with involuntary movement disorders, which should be assessed by a healthcare professional.
Mood stabilisers include lithium and some anticonvulsant medicines. The safety requirements vary substantially between products. People taking lithium, for example, generally require monitoring of lithium levels and kidney and thyroid function.
Stimulant medicines used for conditions such as ADHD can affect sleep and may raise heart rate and blood pressure. Side effects and monitoring requirements depend on the specific medicine and the person taking it.
Supplements can matter too. “Natural” does not necessarily mean interaction-free. St John’s wort, for example, can affect the serotonin system and may interact with antidepressants and other medicines. Make sure your doctor or pharmacist knows about vitamins, herbal products and supplements you take.
Some symptoms have their own more detailed guides. See mental health medication weight gain if your concern involves changes in weight, or mental health medication causing drowsiness if excessive sleepiness or reduced alertness is the main problem.
Red flags: when this symptom may need urgent medical attention
Most medicine side effects are not medical emergencies, but some symptoms should not be watched at home while waiting to see whether they improve.
Seek urgent medical help if you develop difficulty breathing, swelling of the face, lips, tongue or throat, a severe or rapidly spreading rash, fainting, a seizure, severe chest pain, severe confusion, uncontrolled movements accompanied by significant illness, or another sudden and severe reaction.
New or worsening suicidal thoughts, thoughts of self-harm or behaviour suggesting an immediate risk of harm also need urgent help. Some people, particularly younger people taking antidepressants, may experience increased suicidal thinking after treatment is started or the dose is changed, so significant mood or behavioural deterioration should be taken seriously.
Another uncommon but potentially dangerous reaction is serotonin syndrome. It can occur when medicines or supplements that increase serotonin are combined or, in some situations, during changes to serotonergic treatment. Warning signs can include marked agitation or confusion, high temperature, sweating, a fast heartbeat, muscle twitching, tremor, rigidity or other unusual neuromuscular symptoms.
Read more about serotonin syndrome symptoms and our guide to serious medication side effects.
If your symptoms are not an emergency but are persistent, worsening, interfering with everyday activities or making you concerned about continuing treatment, see when to see a doctor for medication side effects.
What to track before speaking to a doctor or pharmacist
A short symptom record can make it easier for a healthcare professional to work out what may be happening. You do not need to prove that your medicine caused the problem. Simply record what you notice as accurately as possible.
Useful details include:
- the medicine name, strength and dose you are taking; when treatment started and whether the dose recently changed; when each symptom began and how long it lasts; whether symptoms appear at a particular time after taking the medicine; how severe the symptoms are and whether they are improving or worsening; changes in sleep, appetite, weight, sexual function, mood or concentration; any prescription medicines, pharmacy medicines, vitamins, herbal remedies or supplements taken at the same time; any missed or additional doses; and how the symptoms affect normal activities such as driving, working, studying, eating or sleeping.
Bring the medicine packaging or an up-to-date medicine list to your appointment if possible. Your pharmacist can also help you identify active ingredients, possible duplicate medicines and known interactions.
Do not rely only on general online side-effect lists. The professional information or patient leaflet for the specific medicine is important because side effects, contraindications and monitoring requirements differ from one product to another.
What not to do without medical advice
Do not stop a prescribed mental health medicine simply because you develop a possible side effect unless you are receiving emergency medical instructions to do so.
Stopping some medicines abruptly can cause withdrawal symptoms, a return or worsening of the condition being treated, or other complications. NIMH advises that prescribed mental health medication should not be stopped without the help of a healthcare professional, who can determine whether the dose needs to be reduced gradually or whether another approach is appropriate.
Do not double your next dose to compensate for a missed dose unless the medicine’s instructions or a healthcare professional specifically tell you to do so. Avoid changing the dose, timing or frequency yourself.
Do not add herbal products or supplements in an attempt to counteract a side effect without checking for interactions. Tell your doctor or pharmacist about everything you take, including non-prescription products.
If a medicine is making you very sleepy, dizzy, confused or poorly coordinated, avoid driving, cycling or using machinery until you have obtained appropriate advice and know how the medicine affects you.
Related side-effect guides and reporting options in South Africa
If you are experiencing a possible medicine reaction, the next step depends on its severity. Emergency symptoms need immediate medical care. Persistent or troublesome symptoms should be discussed with the doctor who prescribed the medicine or with a pharmacist.
South Africans can also report suspected adverse reactions to SAHPRA. SAHPRA’s Med Safety system allows members of the public as well as healthcare professionals to submit suspected adverse drug reaction reports. Reporting does not require you to prove that the medicine caused the reaction; suspected reactions contribute to medicine-safety monitoring.
See how to report side effects in South Africa.
For symptoms involving medicines outside the mental health category, browse the side effect symptoms A-Z or the broader guide to medication side effects.
Is this a common side effect?
That depends on the medicine and the symptom. A symptom that is common with one antidepressant, antipsychotic or mood stabiliser may be unusual with another. Check the patient information for the exact product and ask a doctor or pharmacist if you are uncertain.
How long can mental health medication side effects last?
Some side effects appear early and improve as the body adjusts. Others can continue for as long as the medicine is taken or develop only after longer treatment. Duration depends on the medicine, dose and individual response, so persistent or worsening symptoms should be reviewed rather than assumed to be temporary.
Should I stop the medicine if I think it is causing side effects?
Do not stop or change a prescribed mental health medicine on your own. Contact a doctor or pharmacist for advice. They can assess the symptoms and decide whether monitoring, a dose adjustment, a gradual change of treatment or another intervention is appropriate.
When should I seek help?
Seek immediate medical attention for severe allergic reactions, breathing difficulty, seizures, fainting, severe chest pain, severe confusion, suicidal thoughts or other rapidly worsening or dangerous symptoms. For less severe symptoms that persist, worsen or interfere with daily life, speak to a doctor or pharmacist.
Medical disclaimer: This information is for general education and is not a diagnosis or a substitute for individual medical advice. Side effects and safety requirements differ between medicines and patients. Speak to a doctor or pharmacist about symptoms that concern you, and seek urgent medical help for severe or rapidly worsening reactions.