“The trouble with the drugs is actually disentangling what is the effect of the drug and what’s the effect of the depression. It’s so difficult to tell.” – Stuart.

Stuart’s observation sums up a problem that a number of people we spoke to identified, about how difficult it can be to know whether a particular feeling or symptom is a side effect of the antidepressant, or a symptom of the illness itself.

People we talked to described a variety of symptoms that they believed to be side effects of antidepressants, both physical and psychological. Headaches, stomach upsets, numbness, insomnia, wanting to sleep more, feeling detached from reality, loss of concentration, or memory problems may be typical symptoms of depression, but were also identified as side effects of the medicines (see Coping with antidepressant side effects).

Hannah said she wasn’t always sure whether to go back to see her GP about side effects because “sometimes you don’t know if how you’re feeling is as a result of the depression or whether it is actually a side effect.”

When Gerry first started taking an antidepressant he described feeling a heightened sense of anxiety and that “it didn’t feel that much different from having depression, in terms of… I still felt depressed but at the same time I felt like ‘spaced out’.”

Dina thought that antidepressants had affected her appetite but said “I don’t know, if it was the drug… I can’t tell whether it was actually a side effect or if it was just the suppression of appetite that I get when I’m depressed anyway, that’s hard to tell.”

Commonly people felt worried when they read the possible side effects listed in the patient information leaflet, which some people noted could be strikingly similar to the symptoms of depression.

Melanie was unsure about taking an antidepressant when she read the leaflet and went back to see the GP for reassurance. “There were certain bits of it that I thought… You know, a lot of the symptoms were things that, a lot of the side effects of the medication were things that I was already suffering as symptoms of the depression.”

Some people worried that taking an antidepressant could make them feel worse rather than better. People who were experiencing severe or serious depression had concerns about the increased risk of suicidal feelings that an antidepressant can potentially precipitate. Rachel observed, “It seems to repeat the symptoms of what you’re suffering from already… you may feel suicidal.”

Lou said she experienced heightened feelings of anxiety when she started on Seroxat (paroxetine). “I was feeling depressed before, but this was really bad, because of the medication.”

Some people we interviewed had other health conditions which could also cause similar symptoms. Sonia had suffered from migraines all her life and said it was difficult to tell whether the increased number of headaches she experienced could be linked with the antidepressant sertraline. Emma had a neurological problem which caused difficulties concentrating and with memory, so she couldn’t be certain what was a consequence of the neurological impairment, what might be a side effect of Cipramil, or a symptom of her depression.

Dina put on weight with mirtazipine, but recognised that she also used to comfort eat as part of her depression and felt that “the weight gain isn’t just about the drugs.”

One example people gave of how difficult it is to tell a side effect from a symptom is in relation to sex. Some people experienced loss of libido, had difficulties climaxing, or were totally disinterested in sex when they were taking an antidepressant, but it wasn’t always clear whether this could be attributed to the antidepressant, as these problems can also be symptoms of depressive illness.

Michael remembered that his wife had thought his lack of interest in sex was a side effect of taking antidepressants. “She said it was the pills that were making me not interested in sex and the doctor said ‘No it isn’t, that’s his depression’.”

Charlotte said her loss of libido had caused problems between her and her boyfriend, which she partly attributed to venlafaxine, but also said that the circumstances at the time, and feeling so depressed, had made her lose interest in sex.

(See also Coping with antidepressant side effects,’Starting to take an antidepressant, Reviewing antidepressant use and The patient information leaflet).