Over two-thirds (68%) of people with asthma who responded to a survey by the charity said their sex lives have been directly affected by their condition.
Callie-Anne, 31, said her sex life with her husband was put "on hold" because of her severe asthma.
The charity said it may be a sign that people do not have the disease under control and they should seek advice.
Callie-Anne said she was not surprised at the results of the survey as "people are suffering in silence".
"It's just not spoken about. I've been asked how it affects my children, my work, my studying, my social life by many doctors, consultants, healthcare workers and just general people even on the asthma forums.
"It's very rare anyone asks how it affects my relationship with my husband and no-one would ever ask how it affects the intimate part of our relationship."
But she said her condition has a significant effect on her love life.
"I often start wheezing loudly during sex and feel like my chest will explode because I can't get air out of my lungs. I have to stop so I can take my inhaler and catch my breath.
"This can be really embarrassing and frustrating and for a long time after I was diagnosed I was too scared to have sex or be intimate."
The charity said a number of respondents echoed Callie-Anne's experience and reduced the amount of sex they had, or stopped having it altogether.
Nearly half (46%) of the 544 people who responded said they would be more sexually confident if they did not have asthma.
The survey found that just under 15% felt their asthma had contributed to a relationship finishing, with one respondent revealing that theirs had been ended in an ambulance, during an asthma attack "because my boyfriend said I was causing him stress and he couldn't cope. I ended up going to the hospital alone".
A number also said they have been admitted to hospital because an orgasm triggered an asthma attack, while others reported problems with performing oral sex because of breathing difficulties.
The charity is hoping more asthma sufferers will now talk about how it affects their love lives.
"We were not expecting the level of response we received to our survey, nor the degree to which so many people are struggling with their asthma," said Dr Andy Whittamore, Asthma UK's in-house GP.
"The condition can have a tremendous impact on people's ability to have fulfilling love and sex lives, causing embarrassment and discomfort.
"As a result, some people may feel too embarrassed to speak to their GP or asthma nurse, but if their asthma symptoms are preventing them from having a healthy love life their asthma may not be under control and they need to seek help."
Callie-Anne said an honest conversation between her and her husband put them back on track.
"We had been keeping our feelings to ourselves out of fear of burdening each other with more stress. But this was making things worse.
"One day I sat him down and explained how I felt about my severe asthma and that I was worried he no longer wanted me. He looked at me like I was crazy.
"He said he was scared to initiate sex because once when he did, it triggered my symptoms and I had an asthma attack. He also said he didn't know how to approach the issue with me because of my mood swings and felt helpless that he couldn't help me.
"We're now more open and honest with each other and, when it comes to sex, we've learned to just roll with it. If I start getting symptoms and I need to stop to use my nebuliser or inhaler, we just laugh and joke about how hot I look with a nebuliser mask on."
Five tips for sufferers
Don't be embarrassed: Remember that asthma is a common condition and it is likely that your date/partner will not mind if you need to use your inhaler on a date or during sex. If you are in a relationship, communication with your partner is key and can help you both feel more confident about your asthma and better understand each other's needs.
Know your triggers: If you get any difficulties with triggers such as alcohol, different smells and even an allergy to latex, it is worth talking it through with your partner in advance so you can make any necessary adjustments.
Take note of your symptoms: If you notice that you are getting asthma symptoms during sex, such as coughing, wheezing or shortness of breath, it is probably an indication that your asthma is not as well controlled as it could be. If this is the case, you should make an appointment to see your GP or asthma nurse.
Reduce your risk: The best way to avoid getting asthma symptoms during sex is to manage your asthma well. There are several ways you can keep your asthma in check, including: taking your medicine as prescribed, checking your inhaler technique with your GP or asthma nurse, using a written asthma action plan and going to regular asthma reviews.
Speak to someone: Do not be afraid to speak to your GP or asthma nurse about how asthma may be interfering with your personal life, your relationships, or your sex life. You can also call to speak to nurses on the Asthma UK Helpline.
Source: Asthma UK